Dear CTPP Listserv members,

In June 2021 the CTPP Oversight Board submitted a request to the Census Bureau for the next CTPP package based on 2017-2021 American Community Survey (ACS) survey data.  Census Bureau staff, including the Disclosure Review Board (DRB), ACS staff, and Journey-to-Work subject matter experts responded in January 2022 with a memo outlining disclosure concerns and delineating proposed rules for this CTPP special tabulation.  The impact of these rules will affect the CTPP package and the Table Subcommittee of the AASHTO Oversight Board is working hard to try and preserve a quality product.

The Census Bureau’s concerns, and proposed rules include:

1. Reduce the overall size of the package
2. Standardization of Universes, Variables, and Categories wherever possible to match standard Census ACS products
3. Perturbation techniques must be employed
4. Any flow must be subject to an unweighted minimum of 3 persons.  This means 3 people had to respond to the ACS that they live in one geography and work in the other.
5. Non-residence geographies must have 50 unweighted cases to avoid suppression.  This means that part 2 (workplace) data at small geography will be in jeopardy of being suppressed
6. Mean and Aggregate tables must have a minimum of 3 to be tabulated

As a result of the memo and its implications, the Table Subcommittee is developing a response to the Census Bureau to determine a path forward.  We have been working with industry experts on that response.  To date, our strategy involves:

1. Eliminating block groups in parts 2 and 3 and much of part 1.  (A small list of part 1 tables at the block group level is TBD)
2. Universes, variables, and categories/cohorts will be standardized to the extent possible
3. Developing a sound justification for keeping CTPP-specific universes, variables, or categories
4. Expecting perturbation decisions to be data driven and originate at the CB
5. Documenting the loss of data that occurs when the rule of 3 for flows is implemented
6. Mean and Aggregate tables with less than 3 are not very meaningful and are a disclosure risk

Where we have significant issues are the 50 unweighted cases at the workplace that renders much of the package useless for parts 2 and 3.  We are exploring options such as not having the requirement for a small set of tables or employing either perturbation or synthesizing techniques to supplement what the DRB will approve.

The work is ongoing to respond to the Census Bureau.  If you have concerns about what is going, please reach out to Arash, Penelope or me.

Clara, Arash, and Penelope