CTPP

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3069 discussions

Re: [CTPP] Please delete my e-mail address from the CTPP e-mail list

by MBrienzo＠ci.lincoln.ne.us

I agree. Please remove my name as well. Thank you. "DeBrower, Brad" <BradD(a)cedar-rapi To: ds.org> "'ctpp-news(a)chrispy.net'" Sent by: <ctpp-news(a)chrispy.net> owner-ctpp-news(a)c cc: hrispy.net Subject: [CTPP] Please delete my e-mail address from the CTPP e-mail list 01/28/2002 03:36 PM Please delete my e-mail address from the CTPP e-mail list. There is just too much unnecessary junk associated with being on that list. Thank you. Brad DeBrower bradd(a)cedar-rapids.org

23 years, 6 months

[CTPP] Please delete my e-mail address from the CTPP e-mail list

by DeBrower

Please delete my e-mail address from the CTPP e-mail list. There is just too much unnecessary junk associated with being on that list. Thank you. Brad DeBrower bradd(a)cedar-rapids.org

23 years, 6 months

RE: [CTPP] Purpose of this forum

by JShrum

James, I could not agree with you more!!! Let me know if you find another board that has some relevant and pertinent information. - Jeff -----Original Message----- From: James Dagostino [mailto:jdagostino(a)smtcmpo.org] Sent: Monday, January 28, 2002 3:10 PM To: 'ctpp-news(a)chrispy.net' Subject: [CTPP] Purpose of this forum I signed up for this forum for education on pertinent census 2000 data issues and the release of ctpp. Instead I get an endless barrage of emails from people ripping into each other. Is there a forum where the actual topic is the census data without the bickering. -Jim James D'Agostino SMTC 126 North Salina Street, Suite 100 Syracuse, New York 13202 Telephone: (315) 422-5716 Fax: (315) 422-7753 E-Mail: jdagostino(a)smtcmpo.org -----Original Message----- From: Patty Becker [mailto:pbecker(a)umich.edu] Sent: Monday, January 28, 2002 2:33 PM To: rlamacchia(a)geo.census.gov Cc: ctpp-news(a)chrispy.net Subject: RE: [CTPP] Some more points Bob, This is getting a bit silly, and more than a little bit defensive. I stand corrected on the use of the computer for 1980 bgs. But doing them manually on the tables in Jeffersonville amounted to the same thing: accidental geography. The bureau had no information about the logical location of sub-tract lines and they were not yet in the "co-op" program. In the mid-1970s, I was part of the Detroit area tract committee but did not become its chair (and therefore key person) until the major tracting work was done, because of the huge job I was doing on Detroit's tracts. I do not recall seeing the document you reference, and I KNOW that no one here in the Detroit area paid any attention to it. We were concerned only with tracts. I suspect that was also true elsewhere because no one had ever seen data for block groups and consequently they didn't have a lot of meaning. Also, remember, the mid-1970s marked just the beginning of the regional geographers program, and so there was confusion about what could and couldn't be done locally. This was much clearer 10 years later. I am not arguing that the bureau has not been cooperative with data users. You have. That's not the issue. The issue is (1) most local areas do not have people who pay or paid attention to this stuff, and (2) the data for block groups is still lousy. The latter is not a Geography Division issue; it's a simple fact of the data. I never thought that any one argued comparability for block groups. (Good thing, too.) I was responding to your statement that comparability is the #1 issue for census tracts, as compared to TAZs. Hope this helps. Patty At 01:25 PM 01/28/2002 -0500, Robert LaMacchia wrote: >Patty.. > >I need to correct you again. Since I was in charge of the Master Reference >File development, and the GBF/DIME File program for 1980, I have no idea >where you received your information about the computer delineating the block >groups. For the 1980 census, the block numbering was done manually in >Jeffersonville, IN. This was done using prestype on acetate overlays, >after all of the statistical units that the blocks had to recognize >(including census tracts and block groups) were delineated. As you know, >only that portion of the nation that was estimated to be inside what was to >become 1980 urbanized areas was block numbered, plus those few states that >contracted with the Census Bureau for statewide block numbering. > >For those areas with GBF/DIME files, the Census Bureau had guidelines >"Procedures for Defining, Numbering, and Renumbering Census Block Groups and >Blocks (GEO-307)" that was provided to the local groups updating the >Metropolitan Map Series map sheets and the GBF/DIME Files. That was clearly >a manual process as well. For tabulation, the Census Bureau created the >Master Reference File (MRF) from transcribing the list of census tracts and >blocks from the map sheets. > >As you know, I disagree with you on many of your assumptions and desires >about census geographic areas. As a Census Tract Key Person for the 1970 >census, and my discussions with data users, as well as the comments and >suggestions the Geography Division staff receive throughout the decade and >in response to the official requests for comments, I strongly believe the >Census Bureau has responded extremely well to the data user community in the >establishment of the geographic areas. I would hasten to add that many of >our geographers in the Regional Offices did review and adjust block groups >where the local participant declined to undertake that phase of the program >for 2000. We also made special efforts in our guidelines to point out the >issue of data reliability at the BG level. I quote from the guidelines: > >"Comparability is not a significant concern for BGs. The Census Bureau >recommends combining a BG into an adjacent BG or revising the BG when >the population of a BG is below the minimum required population >threshold. Participants should be aware that sample data reported for >small BGs are subject to increased levels of variability because of the >small >number of people and housing units included in the sample. A participant >may propose retaining unchanged BGs below the minimum population >threshold but the participant must provide written justification for >retaining any BG having a 1990 census population of 600 or less. The >retention of these BGs for Census 2000 is at the discretion of the Census >Bureau. Refer to the section on BGs below the minimum population in this >chapter for further information." > > >Bob LaMacchia > >-----Original Message----- >From: owner-ctpp-news(a)chrispy.net [mailto:owner-ctpp-news(a)chrispy.net]On >Behalf Of Patty Becker >Sent: Monday, January 28, 2002 11:51 AM >To: rlamacchia(a)geo.census.gov; ctpp-news(a)chrispy.net >Subject: RE: [CTPP] Some more points > > >Bob, > >Well, > >The first block groups, in 1980, were definitely done by computer. They >had no human input. After they were done, the bureau decided include long >form data by block group on STF3, and the private sector loved it. (This >was the replacement for Fifth Count File C, which for 1970 had provided >data by enumeration district.) > >For 1990, most block groups stayed the same. Yes, it's true that the RO >staff did the BNA splits (usually down main roads, which meant areas that >were meaningless statistically), and we in the tract committees did have >the opportunity to recommend block group lines. I just don't think that >was done very often; it's hard enough to get people to do tracts. So, for >the most part, the 1980 accidental geography remained in place. STF3 was >expanded considerably so more data were available by block group. > >I have no sense that there was anything different this time than in 1990, >except that you added that useless fourth digit and renumbered blocks >within BG and tract. So, I stand by my original statement for areas which >did not have good local intervention: block groups are accidental geography >and not statistical geography. > >Re TAZs: yes, the purposes are very different. However, in the Detroit >area and I'm sure in lots of other places, TAZs tend to follow tract lines >in residential areas (where there is no high employment density). Of >course the tracts are split up in downtowns and other high attractor >areas. TAZs don't change very much either unless there are major land use >changes that change their status as residential or attractor areas. > >As you know, I disagree with the fundamental point that the main objective >in tracts is comparability over time. The main objective is tracts that >work well now and into the future. Most of the time in most places, the >changes are small enough that most tracts can and should be maintained from >census to census, but comparability is not the main reason. The main >reason is that the characteristics that make a good tract haven't >changed. I know that you are quoting the official Census Bureau "line" >about these matters. I am trying to help people understand what's really >happening. Long form block group data are lousy. > >Someday, we're going to have another geographic conference where we can >discuss these things. Meanwhile, you might want to look at a paper I wrote >for PAA a couple of years ago. If you don't have a copy, I'll be happy to >send it to you. > >----------------------- > >In response to the writers from Spokane, Missouri, and RI: > >Those of you who have specifically delineated block groups are in that 5% >(OK, maybe 10%) in the nation. I agree that people working in small metros >and who are already concerned about their tracts are most likely to do the >work. The more, the better! I'm all for it. However, it's still true >that the vast majority of block groups are not specifically drawn as >statistical geography. (As Bob LaMacchia mentioned, the bgs in the 1990 >BNAs were drawn in the regional offices with an eye toward meeting field >work needs; these needs are very different from those of data users!) > >The important thing for everyone to remember, though, is the essential >shakiness of bg data. Your error rates are very high. > >Yes, the Detroit metro area is more than 10 times the size of Spokane, so >it makes it easier to use tracts here. Congratulations to RI for >merging/nesting census and TAZ geography, I think that's the best way to do >it. > >Patty Becker > >------------------------------------------------------- > >Patricia C. (Patty) Becker 248/354-6520 > >APB Associates/SEMCC FAX 248/354-6645 > >28300 Franklin Road Home 248/355-2428 > >Southfield, MI 48034 pbecker(a)umich.edu ---------------------------------------------------------------------------- --------------------- Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu

23 years, 6 months

RE: [CTPP] Purpose of this forum

by Fritsch

I agree!!! I just erased all ctpp e-mails from today without reading them. Let me know when some important news occurs. Thomas Fritsch Senior Planner AMATS 330 375-2436 fritsto(a)ci.akron.oh.us -----Original Message----- From: James Dagostino [mailto:jdagostino(a)smtcmpo.org] Sent: Monday, January 28, 2002 3:10 PM To: 'ctpp-news(a)chrispy.net' Subject: [CTPP] Purpose of this forum I signed up for this forum for education on pertinent census 2000 data issues and the release of ctpp. Instead I get an endless barrage of emails from people ripping into each other. Is there a forum where the actual topic is the census data without the bickering. -Jim James D'Agostino SMTC 126 North Salina Street, Suite 100 Syracuse, New York 13202 Telephone: (315) 422-5716 Fax: (315) 422-7753 E-Mail: jdagostino(a)smtcmpo.org -----Original Message----- From: Patty Becker [mailto:pbecker(a)umich.edu] Sent: Monday, January 28, 2002 2:33 PM To: rlamacchia(a)geo.census.gov Cc: ctpp-news(a)chrispy.net Subject: RE: [CTPP] Some more points Bob, This is getting a bit silly, and more than a little bit defensive. I stand corrected on the use of the computer for 1980 bgs. But doing them manually on the tables in Jeffersonville amounted to the same thing: accidental geography. The bureau had no information about the logical location of sub-tract lines and they were not yet in the "co-op" program. In the mid-1970s, I was part of the Detroit area tract committee but did not become its chair (and therefore key person) until the major tracting work was done, because of the huge job I was doing on Detroit's tracts. I do not recall seeing the document you reference, and I KNOW that no one here in the Detroit area paid any attention to it. We were concerned only with tracts. I suspect that was also true elsewhere because no one had ever seen data for block groups and consequently they didn't have a lot of meaning. Also, remember, the mid-1970s marked just the beginning of the regional geographers program, and so there was confusion about what could and couldn't be done locally. This was much clearer 10 years later. I am not arguing that the bureau has not been cooperative with data users. You have. That's not the issue. The issue is (1) most local areas do not have people who pay or paid attention to this stuff, and (2) the data for block groups is still lousy. The latter is not a Geography Division issue; it's a simple fact of the data. I never thought that any one argued comparability for block groups. (Good thing, too.) I was responding to your statement that comparability is the #1 issue for census tracts, as compared to TAZs. Hope this helps. Patty At 01:25 PM 01/28/2002 -0500, Robert LaMacchia wrote: >Patty.. > >I need to correct you again. Since I was in charge of the Master Reference >File development, and the GBF/DIME File program for 1980, I have no idea >where you received your information about the computer delineating the block >groups. For the 1980 census, the block numbering was done manually in >Jeffersonville, IN. This was done using prestype on acetate overlays, >after all of the statistical units that the blocks had to recognize >(including census tracts and block groups) were delineated. As you know, >only that portion of the nation that was estimated to be inside what was to >become 1980 urbanized areas was block numbered, plus those few states that >contracted with the Census Bureau for statewide block numbering. > >For those areas with GBF/DIME files, the Census Bureau had guidelines >"Procedures for Defining, Numbering, and Renumbering Census Block Groups and >Blocks (GEO-307)" that was provided to the local groups updating the >Metropolitan Map Series map sheets and the GBF/DIME Files. That was clearly >a manual process as well. For tabulation, the Census Bureau created the >Master Reference File (MRF) from transcribing the list of census tracts and >blocks from the map sheets. > >As you know, I disagree with you on many of your assumptions and desires >about census geographic areas. As a Census Tract Key Person for the 1970 >census, and my discussions with data users, as well as the comments and >suggestions the Geography Division staff receive throughout the decade and >in response to the official requests for comments, I strongly believe the >Census Bureau has responded extremely well to the data user community in the >establishment of the geographic areas. I would hasten to add that many of >our geographers in the Regional Offices did review and adjust block groups >where the local participant declined to undertake that phase of the program >for 2000. We also made special efforts in our guidelines to point out the >issue of data reliability at the BG level. I quote from the guidelines: > >"Comparability is not a significant concern for BGs. The Census Bureau >recommends combining a BG into an adjacent BG or revising the BG when >the population of a BG is below the minimum required population >threshold. Participants should be aware that sample data reported for >small BGs are subject to increased levels of variability because of the >small >number of people and housing units included in the sample. A participant >may propose retaining unchanged BGs below the minimum population >threshold but the participant must provide written justification for >retaining any BG having a 1990 census population of 600 or less. The >retention of these BGs for Census 2000 is at the discretion of the Census >Bureau. Refer to the section on BGs below the minimum population in this >chapter for further information." > > >Bob LaMacchia > >-----Original Message----- >From: owner-ctpp-news(a)chrispy.net [mailto:owner-ctpp-news(a)chrispy.net]On >Behalf Of Patty Becker >Sent: Monday, January 28, 2002 11:51 AM >To: rlamacchia(a)geo.census.gov; ctpp-news(a)chrispy.net >Subject: RE: [CTPP] Some more points > > >Bob, > >Well, > >The first block groups, in 1980, were definitely done by computer. They >had no human input. After they were done, the bureau decided include long >form data by block group on STF3, and the private sector loved it. (This >was the replacement for Fifth Count File C, which for 1970 had provided >data by enumeration district.) > >For 1990, most block groups stayed the same. Yes, it's true that the RO >staff did the BNA splits (usually down main roads, which meant areas that >were meaningless statistically), and we in the tract committees did have >the opportunity to recommend block group lines. I just don't think that >was done very often; it's hard enough to get people to do tracts. So, for >the most part, the 1980 accidental geography remained in place. STF3 was >expanded considerably so more data were available by block group. > >I have no sense that there was anything different this time than in 1990, >except that you added that useless fourth digit and renumbered blocks >within BG and tract. So, I stand by my original statement for areas which >did not have good local intervention: block groups are accidental geography >and not statistical geography. > >Re TAZs: yes, the purposes are very different. However, in the Detroit >area and I'm sure in lots of other places, TAZs tend to follow tract lines >in residential areas (where there is no high employment density). Of >course the tracts are split up in downtowns and other high attractor >areas. TAZs don't change very much either unless there are major land use >changes that change their status as residential or attractor areas. > >As you know, I disagree with the fundamental point that the main objective >in tracts is comparability over time. The main objective is tracts that >work well now and into the future. Most of the time in most places, the >changes are small enough that most tracts can and should be maintained from >census to census, but comparability is not the main reason. The main >reason is that the characteristics that make a good tract haven't >changed. I know that you are quoting the official Census Bureau "line" >about these matters. I am trying to help people understand what's really >happening. Long form block group data are lousy. > >Someday, we're going to have another geographic conference where we can >discuss these things. Meanwhile, you might want to look at a paper I wrote >for PAA a couple of years ago. If you don't have a copy, I'll be happy to >send it to you. > >----------------------- > >In response to the writers from Spokane, Missouri, and RI: > >Those of you who have specifically delineated block groups are in that 5% >(OK, maybe 10%) in the nation. I agree that people working in small metros >and who are already concerned about their tracts are most likely to do the >work. The more, the better! I'm all for it. However, it's still true >that the vast majority of block groups are not specifically drawn as >statistical geography. (As Bob LaMacchia mentioned, the bgs in the 1990 >BNAs were drawn in the regional offices with an eye toward meeting field >work needs; these needs are very different from those of data users!) > >The important thing for everyone to remember, though, is the essential >shakiness of bg data. Your error rates are very high. > >Yes, the Detroit metro area is more than 10 times the size of Spokane, so >it makes it easier to use tracts here. Congratulations to RI for >merging/nesting census and TAZ geography, I think that's the best way to do >it. > >Patty Becker > >------------------------------------------------------- > >Patricia C. (Patty) Becker 248/354-6520 > >APB Associates/SEMCC FAX 248/354-6645 > >28300 Franklin Road Home 248/355-2428 > >Southfield, MI 48034 pbecker(a)umich.edu ---------------------------------------------------------------------------- --------------------- Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu ***COA Virus scanned***

23 years, 6 months

[CTPP] Purpose of this forum

by James Dagostino

I signed up for this forum for education on pertinent census 2000 data issues and the release of ctpp. Instead I get an endless barrage of emails from people ripping into each other. Is there a forum where the actual topic is the census data without the bickering. -Jim James D'Agostino SMTC 126 North Salina Street, Suite 100 Syracuse, New York 13202 Telephone: (315) 422-5716 Fax: (315) 422-7753 E-Mail: jdagostino(a)smtcmpo.org -----Original Message----- From: Patty Becker [mailto:pbecker(a)umich.edu] Sent: Monday, January 28, 2002 2:33 PM To: rlamacchia(a)geo.census.gov Cc: ctpp-news(a)chrispy.net Subject: RE: [CTPP] Some more points Bob, This is getting a bit silly, and more than a little bit defensive. I stand corrected on the use of the computer for 1980 bgs. But doing them manually on the tables in Jeffersonville amounted to the same thing: accidental geography. The bureau had no information about the logical location of sub-tract lines and they were not yet in the "co-op" program. In the mid-1970s, I was part of the Detroit area tract committee but did not become its chair (and therefore key person) until the major tracting work was done, because of the huge job I was doing on Detroit's tracts. I do not recall seeing the document you reference, and I KNOW that no one here in the Detroit area paid any attention to it. We were concerned only with tracts. I suspect that was also true elsewhere because no one had ever seen data for block groups and consequently they didn't have a lot of meaning. Also, remember, the mid-1970s marked just the beginning of the regional geographers program, and so there was confusion about what could and couldn't be done locally. This was much clearer 10 years later. I am not arguing that the bureau has not been cooperative with data users. You have. That's not the issue. The issue is (1) most local areas do not have people who pay or paid attention to this stuff, and (2) the data for block groups is still lousy. The latter is not a Geography Division issue; it's a simple fact of the data. I never thought that any one argued comparability for block groups. (Good thing, too.) I was responding to your statement that comparability is the #1 issue for census tracts, as compared to TAZs. Hope this helps. Patty At 01:25 PM 01/28/2002 -0500, Robert LaMacchia wrote: >Patty.. > >I need to correct you again. Since I was in charge of the Master Reference >File development, and the GBF/DIME File program for 1980, I have no idea >where you received your information about the computer delineating the block >groups. For the 1980 census, the block numbering was done manually in >Jeffersonville, IN. This was done using prestype on acetate overlays, >after all of the statistical units that the blocks had to recognize >(including census tracts and block groups) were delineated. As you know, >only that portion of the nation that was estimated to be inside what was to >become 1980 urbanized areas was block numbered, plus those few states that >contracted with the Census Bureau for statewide block numbering. > >For those areas with GBF/DIME files, the Census Bureau had guidelines >"Procedures for Defining, Numbering, and Renumbering Census Block Groups and >Blocks (GEO-307)" that was provided to the local groups updating the >Metropolitan Map Series map sheets and the GBF/DIME Files. That was clearly >a manual process as well. For tabulation, the Census Bureau created the >Master Reference File (MRF) from transcribing the list of census tracts and >blocks from the map sheets. > >As you know, I disagree with you on many of your assumptions and desires >about census geographic areas. As a Census Tract Key Person for the 1970 >census, and my discussions with data users, as well as the comments and >suggestions the Geography Division staff receive throughout the decade and >in response to the official requests for comments, I strongly believe the >Census Bureau has responded extremely well to the data user community in the >establishment of the geographic areas. I would hasten to add that many of >our geographers in the Regional Offices did review and adjust block groups >where the local participant declined to undertake that phase of the program >for 2000. We also made special efforts in our guidelines to point out the >issue of data reliability at the BG level. I quote from the guidelines: > >"Comparability is not a significant concern for BGs. The Census Bureau >recommends combining a BG into an adjacent BG or revising the BG when >the population of a BG is below the minimum required population >threshold. Participants should be aware that sample data reported for >small BGs are subject to increased levels of variability because of the >small >number of people and housing units included in the sample. A participant >may propose retaining unchanged BGs below the minimum population >threshold but the participant must provide written justification for >retaining any BG having a 1990 census population of 600 or less. The >retention of these BGs for Census 2000 is at the discretion of the Census >Bureau. Refer to the section on BGs below the minimum population in this >chapter for further information." > > >Bob LaMacchia > >-----Original Message----- >From: owner-ctpp-news(a)chrispy.net [mailto:owner-ctpp-news(a)chrispy.net]On >Behalf Of Patty Becker >Sent: Monday, January 28, 2002 11:51 AM >To: rlamacchia(a)geo.census.gov; ctpp-news(a)chrispy.net >Subject: RE: [CTPP] Some more points > > >Bob, > >Well, > >The first block groups, in 1980, were definitely done by computer. They >had no human input. After they were done, the bureau decided include long >form data by block group on STF3, and the private sector loved it. (This >was the replacement for Fifth Count File C, which for 1970 had provided >data by enumeration district.) > >For 1990, most block groups stayed the same. Yes, it's true that the RO >staff did the BNA splits (usually down main roads, which meant areas that >were meaningless statistically), and we in the tract committees did have >the opportunity to recommend block group lines. I just don't think that >was done very often; it's hard enough to get people to do tracts. So, for >the most part, the 1980 accidental geography remained in place. STF3 was >expanded considerably so more data were available by block group. > >I have no sense that there was anything different this time than in 1990, >except that you added that useless fourth digit and renumbered blocks >within BG and tract. So, I stand by my original statement for areas which >did not have good local intervention: block groups are accidental geography >and not statistical geography. > >Re TAZs: yes, the purposes are very different. However, in the Detroit >area and I'm sure in lots of other places, TAZs tend to follow tract lines >in residential areas (where there is no high employment density). Of >course the tracts are split up in downtowns and other high attractor >areas. TAZs don't change very much either unless there are major land use >changes that change their status as residential or attractor areas. > >As you know, I disagree with the fundamental point that the main objective >in tracts is comparability over time. The main objective is tracts that >work well now and into the future. Most of the time in most places, the >changes are small enough that most tracts can and should be maintained from >census to census, but comparability is not the main reason. The main >reason is that the characteristics that make a good tract haven't >changed. I know that you are quoting the official Census Bureau "line" >about these matters. I am trying to help people understand what's really >happening. Long form block group data are lousy. > >Someday, we're going to have another geographic conference where we can >discuss these things. Meanwhile, you might want to look at a paper I wrote >for PAA a couple of years ago. If you don't have a copy, I'll be happy to >send it to you. > >----------------------- > >In response to the writers from Spokane, Missouri, and RI: > >Those of you who have specifically delineated block groups are in that 5% >(OK, maybe 10%) in the nation. I agree that people working in small metros >and who are already concerned about their tracts are most likely to do the >work. The more, the better! I'm all for it. However, it's still true >that the vast majority of block groups are not specifically drawn as >statistical geography. (As Bob LaMacchia mentioned, the bgs in the 1990 >BNAs were drawn in the regional offices with an eye toward meeting field >work needs; these needs are very different from those of data users!) > >The important thing for everyone to remember, though, is the essential >shakiness of bg data. Your error rates are very high. > >Yes, the Detroit metro area is more than 10 times the size of Spokane, so >it makes it easier to use tracts here. Congratulations to RI for >merging/nesting census and TAZ geography, I think that's the best way to do >it. > >Patty Becker > >------------------------------------------------------- > >Patricia C. (Patty) Becker 248/354-6520 > >APB Associates/SEMCC FAX 248/354-6645 > >28300 Franklin Road Home 248/355-2428 > >Southfield, MI 48034 pbecker(a)umich.edu ---------------------------------------------------------------------------- --------------------- Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu

23 years, 6 months

RE: [CTPP] Some more points

by Patty Becker

Bob, This is getting a bit silly, and more than a little bit defensive. I stand corrected on the use of the computer for 1980 bgs. But doing them manually on the tables in Jeffersonville amounted to the same thing: accidental geography. The bureau had no information about the logical location of sub-tract lines and they were not yet in the "co-op" program. In the mid-1970s, I was part of the Detroit area tract committee but did not become its chair (and therefore key person) until the major tracting work was done, because of the huge job I was doing on Detroit's tracts. I do not recall seeing the document you reference, and I KNOW that no one here in the Detroit area paid any attention to it. We were concerned only with tracts. I suspect that was also true elsewhere because no one had ever seen data for block groups and consequently they didn't have a lot of meaning. Also, remember, the mid-1970s marked just the beginning of the regional geographers program, and so there was confusion about what could and couldn't be done locally. This was much clearer 10 years later. I am not arguing that the bureau has not been cooperative with data users. You have. That's not the issue. The issue is (1) most local areas do not have people who pay or paid attention to this stuff, and (2) the data for block groups is still lousy. The latter is not a Geography Division issue; it's a simple fact of the data. I never thought that any one argued comparability for block groups. (Good thing, too.) I was responding to your statement that comparability is the #1 issue for census tracts, as compared to TAZs. Hope this helps. Patty At 01:25 PM 01/28/2002 -0500, Robert LaMacchia wrote: >Patty.. > >I need to correct you again. Since I was in charge of the Master Reference >File development, and the GBF/DIME File program for 1980, I have no idea >where you received your information about the computer delineating the block >groups. For the 1980 census, the block numbering was done manually in >Jeffersonville, IN. This was done using prestype on acetate overlays, >after all of the statistical units that the blocks had to recognize >(including census tracts and block groups) were delineated. As you know, >only that portion of the nation that was estimated to be inside what was to >become 1980 urbanized areas was block numbered, plus those few states that >contracted with the Census Bureau for statewide block numbering. > >For those areas with GBF/DIME files, the Census Bureau had guidelines >"Procedures for Defining, Numbering, and Renumbering Census Block Groups and >Blocks (GEO-307)" that was provided to the local groups updating the >Metropolitan Map Series map sheets and the GBF/DIME Files. That was clearly >a manual process as well. For tabulation, the Census Bureau created the >Master Reference File (MRF) from transcribing the list of census tracts and >blocks from the map sheets. > >As you know, I disagree with you on many of your assumptions and desires >about census geographic areas. As a Census Tract Key Person for the 1970 >census, and my discussions with data users, as well as the comments and >suggestions the Geography Division staff receive throughout the decade and >in response to the official requests for comments, I strongly believe the >Census Bureau has responded extremely well to the data user community in the >establishment of the geographic areas. I would hasten to add that many of >our geographers in the Regional Offices did review and adjust block groups >where the local participant declined to undertake that phase of the program >for 2000. We also made special efforts in our guidelines to point out the >issue of data reliability at the BG level. I quote from the guidelines: > >"Comparability is not a significant concern for BGs. The Census Bureau >recommends combining a BG into an adjacent BG or revising the BG when >the population of a BG is below the minimum required population >threshold. Participants should be aware that sample data reported for >small BGs are subject to increased levels of variability because of the >small >number of people and housing units included in the sample. A participant >may propose retaining unchanged BGs below the minimum population >threshold but the participant must provide written justification for >retaining any BG having a 1990 census population of 600 or less. The >retention of these BGs for Census 2000 is at the discretion of the Census >Bureau. Refer to the section on BGs below the minimum population in this >chapter for further information." > > >Bob LaMacchia > >-----Original Message----- >From: owner-ctpp-news(a)chrispy.net [mailto:owner-ctpp-news(a)chrispy.net]On >Behalf Of Patty Becker >Sent: Monday, January 28, 2002 11:51 AM >To: rlamacchia(a)geo.census.gov; ctpp-news(a)chrispy.net >Subject: RE: [CTPP] Some more points > > >Bob, > >Well, > >The first block groups, in 1980, were definitely done by computer. They >had no human input. After they were done, the bureau decided include long >form data by block group on STF3, and the private sector loved it. (This >was the replacement for Fifth Count File C, which for 1970 had provided >data by enumeration district.) > >For 1990, most block groups stayed the same. Yes, it's true that the RO >staff did the BNA splits (usually down main roads, which meant areas that >were meaningless statistically), and we in the tract committees did have >the opportunity to recommend block group lines. I just don't think that >was done very often; it's hard enough to get people to do tracts. So, for >the most part, the 1980 accidental geography remained in place. STF3 was >expanded considerably so more data were available by block group. > >I have no sense that there was anything different this time than in 1990, >except that you added that useless fourth digit and renumbered blocks >within BG and tract. So, I stand by my original statement for areas which >did not have good local intervention: block groups are accidental geography >and not statistical geography. > >Re TAZs: yes, the purposes are very different. However, in the Detroit >area and I'm sure in lots of other places, TAZs tend to follow tract lines >in residential areas (where there is no high employment density). Of >course the tracts are split up in downtowns and other high attractor >areas. TAZs don't change very much either unless there are major land use >changes that change their status as residential or attractor areas. > >As you know, I disagree with the fundamental point that the main objective >in tracts is comparability over time. The main objective is tracts that >work well now and into the future. Most of the time in most places, the >changes are small enough that most tracts can and should be maintained from >census to census, but comparability is not the main reason. The main >reason is that the characteristics that make a good tract haven't >changed. I know that you are quoting the official Census Bureau "line" >about these matters. I am trying to help people understand what's really >happening. Long form block group data are lousy. > >Someday, we're going to have another geographic conference where we can >discuss these things. Meanwhile, you might want to look at a paper I wrote >for PAA a couple of years ago. If you don't have a copy, I'll be happy to >send it to you. > >----------------------- > >In response to the writers from Spokane, Missouri, and RI: > >Those of you who have specifically delineated block groups are in that 5% >(OK, maybe 10%) in the nation. I agree that people working in small metros >and who are already concerned about their tracts are most likely to do the >work. The more, the better! I'm all for it. However, it's still true >that the vast majority of block groups are not specifically drawn as >statistical geography. (As Bob LaMacchia mentioned, the bgs in the 1990 >BNAs were drawn in the regional offices with an eye toward meeting field >work needs; these needs are very different from those of data users!) > >The important thing for everyone to remember, though, is the essential >shakiness of bg data. Your error rates are very high. > >Yes, the Detroit metro area is more than 10 times the size of Spokane, so >it makes it easier to use tracts here. Congratulations to RI for >merging/nesting census and TAZ geography, I think that's the best way to do >it. > >Patty Becker > >------------------------------------------------------- > >Patricia C. (Patty) Becker 248/354-6520 > >APB Associates/SEMCC FAX 248/354-6645 > >28300 Franklin Road Home 248/355-2428 > >Southfield, MI 48034 pbecker(a)umich.edu ------------------------------------------------------------------------------------------------- Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu

23 years, 6 months

RE: [CTPP] Some more points

by Patty Becker

Bob, Well, The first block groups, in 1980, were definitely done by computer. They had no human input. After they were done, the bureau decided include long form data by block group on STF3, and the private sector loved it. (This was the replacement for Fifth Count File C, which for 1970 had provided data by enumeration district.) For 1990, most block groups stayed the same. Yes, it's true that the RO staff did the BNA splits (usually down main roads, which meant areas that were meaningless statistically), and we in the tract committees did have the opportunity to recommend block group lines. I just don't think that was done very often; it's hard enough to get people to do tracts. So, for the most part, the 1980 accidental geography remained in place. STF3 was expanded considerably so more data were available by block group. I have no sense that there was anything different this time than in 1990, except that you added that useless fourth digit and renumbered blocks within BG and tract. So, I stand by my original statement for areas which did not have good local intervention: block groups are accidental geography and not statistical geography. Re TAZs: yes, the purposes are very different. However, in the Detroit area and I'm sure in lots of other places, TAZs tend to follow tract lines in residential areas (where there is no high employment density). Of course the tracts are split up in downtowns and other high attractor areas. TAZs don't change very much either unless there are major land use changes that change their status as residential or attractor areas. As you know, I disagree with the fundamental point that the main objective in tracts is comparability over time. The main objective is tracts that work well now and into the future. Most of the time in most places, the changes are small enough that most tracts can and should be maintained from census to census, but comparability is not the main reason. The main reason is that the characteristics that make a good tract haven't changed. I know that you are quoting the official Census Bureau "line" about these matters. I am trying to help people understand what's really happening. Long form block group data are lousy. Someday, we're going to have another geographic conference where we can discuss these things. Meanwhile, you might want to look at a paper I wrote for PAA a couple of years ago. If you don't have a copy, I'll be happy to send it to you. ----------------------- In response to the writers from Spokane, Missouri, and RI: Those of you who have specifically delineated block groups are in that 5% (OK, maybe 10%) in the nation. I agree that people working in small metros and who are already concerned about their tracts are most likely to do the work. The more, the better! I'm all for it. However, it's still true that the vast majority of block groups are not specifically drawn as statistical geography. (As Bob LaMacchia mentioned, the bgs in the 1990 BNAs were drawn in the regional offices with an eye toward meeting field work needs; these needs are very different from those of data users!) The important thing for everyone to remember, though, is the essential shakiness of bg data. Your error rates are very high. Yes, the Detroit metro area is more than 10 times the size of Spokane, so it makes it easier to use tracts here. Congratulations to RI for merging/nesting census and TAZ geography, I think that's the best way to do it. Patty Becker ------------------------------------------------------- >Patricia C. (Patty) Becker 248/354-6520 >APB Associates/SEMCC FAX 248/354-6645 >28300 Franklin Road Home 248/355-2428 >Southfield, MI 48034 pbecker(a)umich.edu

23 years, 6 months

RE: [CTPP] Some more points

by millef1＠mail.modot.state.mo.us

I was working for a regional planning commission in the late 90's, and was involved in a review of the tracts and block groups in southwest Missouri. Using the Census Bureau's guidelines, we wanted to identify block groups and tracts that made sense from the standpoint of locally identified communities and neighborhoods. We paid particular attention to geographic features such as roads, lakes, etc. that would contribute to identifying block groups and tracts that would make sense for tabulation. Unfortunately, we lacked a lot of detailed information on housing units and population counts in our rapidly growing rural areas to be more precise with meeting population targets. However, the process was not at all arbitrary - albeit I think it lacked the uniformity that you would have in a major metro area with GIS base data, building permit tracking, etc. to contribute to the process. - Frank Miller Please respond to rlamacchia(a)geo.census.gov To: "Patty Becker" <pbecker(a)umich.edu> cc: ctpp-news(a)chrispy.net (bcc: Frank O Miller/D8/MODOT) Subject: RE: [CTPP] Some more points For Census 2000, the participant statistical areas program asked/allowed/encouraged all participants, nationwide, to review and suggest changes to the the census tracts (including the former BNAs) and BGs. Some participants did review and suggest changes to the BGs, many did not. Where participants did not change the BGs, the geographers in the Regional Offices made any necessary changes in accordance with the guidelines. The guidelines used by participants are on the web at:

23 years, 6 months

RE: [CTPP] Some more points

by Allen

Block group data is and always has been important to the public sector. It has been essential to my activities as a transportation planner over the years. I cannot speak for other areas, but there is nothing "accidental" about the geography of block groups in the areas in which I work. Perhaps this is due to my active interest and involvement in the delineation of all census statistical areas affecting my work. The necessity of meeting minimum goals of persons and households for the sake of statistical analysis does occasionally lead to somewhat arbitrary aggregations of small areas. The necessity of delineating the block group boundaries prior to the actual census does occasionally lead to odd-looking results, especially in rapidly developing or redeveloping areas. Errors made by the Bureau of the Census in field review, in digitizing, or in geocoding are the only cause of "accidental" geography in my experience. For the 1990 census, the Bureau would not allow local entities to demand corrections to Bureau errors below the Census Tract level. In 2000, they are allowing us to demand corrections that affect block groups, but not individual blocks. (My metropolitan area had about half a mile of a major drainage feature eliminated during field review. The Bureau admitted it was their mistake but would not restore the block boundary.) In short, I'll fight over any decisions that diminish my flexibility in performing demographic analyses and would encourage other to do the same. Robert R. Allen, AICP Transportation Planning Director Abilene Metropolitan Planning Organization ph.: 915-676-6243 fax: 915-676-6242 Excerpt from Original Message----- From: owner-ctpp-news(a)chrispy.net [mailto:owner-ctpp-news(a)chrispy.net]On Behalf Of Patty Becker Sent: Sunday, January 27, 2002 12:04 PM To: ctpp-news(a)chrispy.net Subject: [CTPP] Some more points I am skeptical about block group data. They have never been very reliable anyhow, and are mostly important to the private sector because they permit more precise aggregation in what I call radius analyses (1 mile circle, three mile circle, etc.) The long form data at the individual block group level have very high sampling and non-sampling error rates. In addition, block groups are largely "accidental" geography, because the lines between them are most often arbitrary and not based on any real-life criteria. Tracts (and TAZs), on the other hand, are deliberately drawn to meet local criteria, or they should be. I think it would serve us all better to refer to TAZs as tract-equivalents rather than block-group equivalents. In areas without high employment density, that's what they are. I don't think a fight over block group data will serve anyone well as this point.

23 years, 6 months

[CTPP] Some more points

by Patty Becker

Thanks to everyone who commented on my comments. Regarding ACS data delivery, there is a plan in the works which is going to be tested this year. It's called "Tier 3," referring to American FactFinder (tier 1 is the profiles, and tier 2 is the summary file tables, both now available). In Tier 3, the idea is that the user could specify the precise geography and precise cross-tabulation(s) desired, and the system will check to see if the requested table meets confidentiality criteria before delivering it. The table would run off the basic 2000 census record. If Tier 3 works out, it would probably be extended to the ACS files. Thus, for example, a run could be done for a group of tracts with population 65K or higher. This OUGHT to include a standard profile for the custom geography. I definitely agree with the idea of sub-MCD ACS tabulation areas--these are not PUMAs because they're not for microdata. This is an idea to be worked on for the future. I am skeptical about block group data. They have never been very reliable anyhow, and are mostly important to the private sector because they permit more precise aggregation in what I call radius analyses (1 mile circle, three mile circle, etc.) The long form data at the individual block group level have very high sampling and non-sampling error rates. In addition, block groups are largely "accidental" geography, because the lines between them are most often arbitrary and not based on any real-life criteria. Tracts (and TAZs), on the other hand, are deliberately drawn to meet local criteria, or they should be. I think it would serve us all better to refer to TAZs as tract-equivalents rather than block-group equivalents. In areas without high employment density, that's what they are. I don't think a fight over block group data will serve anyone well as this point. The "rolling average" means that while data released at the tract level in 2008 were collected in 2003-7, the 2009 release will include 2004-8 data, and so forth. One of the most important things about the ACS is that it is in the field on a 12 month basis. This is a distinct difference from the census long-form, which is collected as of April 1 (at least in theory) and for which the income data represent the previous calendar year. In ACS, the income data will reflect the past 12 months. Mobile populations will be enumerated where they are at any given time, which means that a town like Gainesville, FL, which has a much lower population count in the summer than in the winter (40K to 100K) will show up with less than 100K population in the ACS. Analysis of these various differences is one of the main purposes of the supplementary surveys, especially the C2SS in 2000. Elaine--good luck on getting 14 tables on the TAZ/TAZ matrix. I'm pretty skeptical given the current climate, especially since the fact that the data go only into models doesn't carry much weight with the DRB. I will be interested to see what happens. I would recommend, though, that you consider giving up some of the detail in the interest of having the counts. About the rule of 100: that is the arbitrary cutoff for presentation of data on SF2. See http://www.census.gov/Press-Release/www/2001/sumfile2.html. SF4 will probably be higher. But again, remember, that the cutoff on these files is designed for the presentation of data for these small race/ethnic groups. It makes sense not to deliver 47 tables for a population group with only 35 (or 99) people in a given geographic area such as a tract or small MCD. You can always look at a higher level of geography, such as the county, to get these characteristics for the (perhaps slightly) larger population count for the group. An important point about SF2, and what I said above, is that the file is PUBLIC. It will be out there on AFF and anyone can look at it. The case needs to be made that the CTPP, data for TAZs, is NOT PUBLIC in the same sense. Eventually they're going to have to work out licensing agreements or something similar to handle this problem. Right now, we're in the crosshairs of the problem without good decisions having been made. As I said before, eternal vigilance is required. Patty Becker Patricia C. (Patty) Becker 248/354-6520 APB Associates/SEMCC FAX 248/354-6645 28300 Franklin Road Home 248/355-2428 Southfield, MI 48034 pbecker(a)umich.edu

23 years, 6 months

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