Data revision history

State Summary/State Characteristics Longitudinal Data File (PUSUM)

Robert E. Molyneux

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Abstract

This page documents a longitudinal set of state summary public library data constructed from two sources. One is the annual Public Library Survey formerly collected by the National Center for Education Statistics (NCES) under the Federal State Cooperative System (FSCS) program and more recently from the continuing series published by the Institute of Museuem and Library services. This compilation is of the State Summary/State Characteristics Data File, that is Public Use Summary (hence, I conclude, PUSUM which convention NCES and IMLS have named files in this series). The dataset now contains 884 observations (an observation being summary data from the libraries in one state for one year), with 66 variables per observation, although not all variables were collected all years. These data are from the states, the District of Columbia, and occasionally territories.

The summary data were originally compiled and published for the years Fiscal Year (FY) 1987-FY 2008 although for reasons discussed shortly, the set of data discussed here only has the data from FY 1992-FY 2008 or 17 years. The data are available in formats discussed at the bottom of the page under Distribution and Formats.

The state summary data are fundamentally different from the Public Library Data File which is a compilation of data from 10,000 public libraries collected from FY 1987-FY 2008. These summary data are the result of analyzing aspects of those data and other data. Given that not all libraries respond to all survey items, NCES and IMLS have imputed those missing data. Documentation is carried in the various sources cited in the list of NCES and IMLS Public Library Survey publications elsewhere on this site. PUSUM contains imputed data given that it is attempting to compensate for the missing values for purposes of arriving at national assessments of the state of public libraries. Knowing this, could you replicate these summary data using the Public Library Data File either in its unimputed or imputed forms? Probably not. The documentation on how the imputations were done is sketchy but improving but does involve data that are masked in the Public Library Data file for privacy reasons so IMLS has access to data suppressed for individual libraries. Data are suppressed in smaller libaries, for instance, salary information when the staff is sufficiently small to cause a privacy concern. Of course, you could do your own imputations. More telling, though, is the fact that these summary files are also constructed using the Restricted Use data, in part. These data are not available for public use.

A further complication follows from this practice of imputation. The documentation for several years (here 2007) specifically warns:

Comparisons to data prior to FY 92 should be made with caution, as earlier data files do not include imputations for nonresponse, and the percentage of libraries responding to a given item varied widely among states. (p. 13)

According to the documentation from earlier years, there are supposed to be summary data from FY 1987-FY 1991. 1991 is made up of a summary from the reporting libraries so that comparing FY 1991 with FY 1992 is likely to show discontinuities that are an artifact of the imputations not from any change in the libraries. For FY 1987-FY 1989, in spite of the documentation's saying there are summary data, they are sketchy. FY 1987 has a few variables reported for the 19 states' summaries reported. Summary data for FY 1988 were not with the rest of the FY 1988 data and I don't know where they are. FY 1989 does have summary data in a separate file as does FY 1990. All imputations could be taken out of the post-1992 data but experimenting with that idea resulted in derivative datasets with very few values. So, we get some data imputed by methods that are not clear or we get vanishly few data.

Variables

The tables below list the variables that were dealt with in constructing PUSUM. The intent was to group all like variables in the various years in one variable name. Rarely was there any ambiguity in reading the documentation from year to year.

Two variables have been added to each year's data in order to ease processing: state and year. (NCES/IMLS variables are in upper case while any non-NCES/IMLS data are in italics. year was hard coded in one of the programs and is the nominal year of collection and the same as the fiscal year that appears on publications. The NCES/IMLS library data have been issued as annual publications without explicit acknowledgement in the data of previous years or years that might follow. State is the two-digit postal code. This variable was made from various variables in the dataset as noted below. All NCLIS datasets use the same conventions.

A spreadsheet (Open Office, xls) presents these variables in another format.

The following table has details on the variables in PUSUM. The convention followed is to use the 2008 variable name except where the data are no longer collected and the short definitions and notes come, largely, from the documentation for FY 2008. The wording differs on occasion for variables documented in the earlier years but the definitions overall are pretty consistent. Imputation flags listed in the documentation are not included in this list nor in PUSUM.

Distribution and Formats

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July 18, 2010

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