Appendix C

Item Response and Imputation for N-SSATS 2011

This Appendix contains Table C.1, a list of item response rates for questions from the N-SSATS 2011 questionnaire. Item non-response was minimized through careful editing and extensive follow-up.

The item response rate for the 2011 N-SSATS averaged 98.6 percent across 195 separate response categories.

Item non-response was 10 percent or more for only 4 of 195 separate response categories.

Imputation was conducted for 11 instances of client values. An imputed value for a service type was assigned if a facility reported that it provided the service but had not provided a client or admissions count for the service.

When available, client values and admissions values from up to five previous surveys were used to impute the missing counts. If historical data were not available, the average client value, stratified by State and facility operation, was used to impute the missing client counts. If a facility were unique in its State and facility operation category, values were imputed using average values for the State only. Missing client counts were imputed for each type of service (i.e., hospital inpatient detoxification, hospital inpatient treatment, residential [non-hospital] detoxification, etc.) and summed to the larger service type totals (total hospital inpatient clients, total residential [non-hospital] clients, and total outpatient clients), and finally to total clients.

Several facilities report client counts for themselves (parent) as well as for other facilities (children) within their family of substance abuse treatment facilities. Instead of reporting only the aggregate client count, we attempted to disaggregate and redistribute or unroll the parent facilities' total client count wherever possible to reflect the number of clients served by each facility within the family of facilities. Our procedure was to first calculate the mean client count per type of care received (hospital inpatient, outpatient, and residential) for the facilities in N-SSATS that reported only for themselves. We then used these means to determine how to distribute the clients reported by a parent facility to its children facilities based on the type of facilities and the types of clients indicated by the family of facilities.

At Synectics, Parth Thakore, Sarbajit Sinha, Doren H. Walker, and Leigh Henderson were responsible for the content, analysis, and writing of the report.

To Table C.1

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