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Quarterly Survey of Public Pensions Methodology

This section describes how the Census Bureau collects the Quarterly Survey of Public Pensions data and how the published data are generated. Select the appropriate topic below for information on the sampling frame, collection periods, collection methods, editing, imputation, sampling error, response rates and nonsampling error.

Population of Interest

The survey collects and publishes data on the financial holdings and activities of the 100 largest defined benefit public employee pension systems based on total cash and security holdings as identified in the most recent Census of Governments: Finance Component. These systems comprise 87.2 percent of financial activity among such entities, based on the 2012 Census of Governments. Financial holdings data show assets in various types of securities such as stocks, bonds, federal notes, and mortgages. Revenue data consist of earnings, as well as contributions from governments and employees. Expenditure data consist primarily of payments to beneficiaries and withdrawals.

Public-employee retirement systems must meet two criteria: (1) they are sponsored by a recognized unit of state or local government as defined by the Census Bureau; and (2) their membership must be comprised of public employees compensated with public funds. These retirement systems consist of defined benefit plans not defined contribution or post-employment healthcare plans.

Data Collection

Data for the Quarterly Survey of Public Pensions have been collected on a quarterly basis since 1968. The collection starts at the beginning of each calendar quarter and continues for about three months. Revenue collected, payments made, and asset amounts are as of the end of each calendar quarter (March, June, September, and December).

Effective with the first quarter of 2012, the Survey of the Finances of Public Employee Retirement Systems was renamed to the Quarterly Survey of Public Pensions (QSPP). Several other modifications and improvements were made to the survey at the same time. In Part 1, realized net gains or losses was separated from unrealized net gains or losses. In Part 3, the asset Federally-sponsored agency securities was moved from Corporate Bonds to Federal Government Securities. Additionally, private equity, venture capital, and leveraged buy-outs were moved from Other Securities to Corporate Stocks.

Usable replies are received from at least 80 percent of the systems canvassed.

Data Processing

Revisions: Revisions reflect amounts obtained from two general sources. State and local government respondents have submitted revisions to amounts as originally reported. In other cases, governments have reported data, which we used to replace data that were previously imputed or estimated. Current revisions are noted in each table by an “R”or, for Table 3, by a label next to the applicable figure, for appropriate quarters

Editing: Editing is a process that ensures survey data are accurate, complete, and consistent. Efforts are made at all phases of collection, processing, and tabulation to minimize errors. Although some edits are built into the Internet data collection instrument and the data entry programs, the majority of the edits are performed after the case has been loaded into the Census Bureau's database.

Edits consist primarily of two types: consistency and a ratio of the current year's reported value to the prior year's value. The consistency edits check the logical relationships of data items reported on the form. For example, if a value exists for the number of retirees receiving benefits because of age or length of service then there must be a value reported for the amount paid. The current quarter/prior quarter edits compare by item code the data reported for the current quarter with data reported for the prior quarter. If data falls out of acceptable tolerance levels, the item is flagged for review. For both types of edits, the edit results are reviewed by analysts and adjusted when needed. When the analyst is unable to resolve or accept the edit failure, contact is made with the respondent to verify or correct the reported data.

Imputation: Not all respondents answer every item on the questionnaire. There are also questionnaires that are not returned despite efforts to gain a response. Imputation is the process of filling in missing or invalid data with reasonable values in order to have a complete data set. Usable replies are received from at least 80 percent of the systems canvassed. Effective in the second quarter of 2013, the Quarterly Survey of Public Pensions (QSPP) improved upon item imputation method to fill in missing data based on grouping similar pension systems together. Both partial and full nonrespondents were imputed using either a mean growth rate, median growth rate, or direct substitution. These methods are applied to certain variables based on research conducted in 2013. A bridge study which reviews the imputation methodology in detail is forthcoming.

Data Quality

Data quality/nonsampling errors:

Although every effort (as described in the Data Processing section) is made in all phases of collection, processing, and tabulation to minimize errors, the data are subject to nonsampling errors such as inability to obtain data for every variable from all units in the panel, inaccuracies in classification, response errors, misinterpretation of questions, mistakes in keying and coding, and coverage errors.

Data in these tables are subject to possible inaccuracies in classification, response, and processing. Every effort is made to keep such errors to a minimum through care in examining, editing, and tabulating the data submitted.

It should be noted that some systems report all or part of receipts and expenditures on an "accrued" basis, and in some cases receipts are accrued but expenditures are on a cash basis. Therefore, the relationship between quarterly revenues and expenditures does not directly tie to an equivalent change in cash and security holdings. However, these differences in the quarterly series will generally be resolved within the fiscal year.

Response Rates

In the table below, the "unit response rate" is the number of units within the 100-member panel who provided data for the QSPP. The unit response rate considers all units equally. The "total quantity response rate" (TQRR) is a response rate that incorporates the size of the unit's assets (denoted by the unit's Z81 value). These two response rates may differ because larger units are more influential than smaller ones. For example, a unit response rate of 87 indicates that 87 units responded; if the TQRR is 90, that means those 87 units represent 90 percent of the assets. For more information about the calculation of TQRRs for economic surveys, please refer to Census Bureau Standard D-3, Appendix B






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