The estimates presented in this report were produced using the NPSAS:2000 Graduate Data Analysis Systems (DAS). The DAS software makes it possible for users to specify and generate their own tables. With the DAS, users can replicate or expand upon the tables presented in this report. In addition to the table estimates, the DAS calculates proper standard errors3 and weighted sample sizes for these estimates. If the number of valid cases is too small to produce a reliable estimate (less than 30 cases), the DAS prints the message "low-N" instead of the estimate.
In addition to tables, the DAS will also produce a correlation matrix of selected variables to be used for linear regression models. Included in the output with the correlation matrix are the design effects (DEFTs) for each variable in the matrix. Since statistical procedures generally compute regression coefficients based on simple random sample assumptions, the standard errors must be adjusted with the design effects to take into account the stratified sampling method used in the NPSAS surveys.
For more information about the NPSAS:2000 and other Data Analysis Systems, consult the NCES DAS website (http://nces.ed.gov/das) or contact:
National Center for Education Statistics
1990 K Street, NW
Washington, DC 20006
Internet address: Aurora.DAmico@ed.gov