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The estimates presented in this report were produced using the B&B:93/97 Data Analysis System (DAS). The DAS software makes it possible for users to specify and generate their own tables from the B&B:93/97 data. 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 (fewer 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 standard errors based on an assumption of simple random sampling, those standard errors must be adjusted with the design effects to take into account B&B’s complex sample design. (See Statistical Procedures section for the adjustment procedure.) For more information about the B&B:93/97 and other Data Analysis Systems, consult the NCES DAS website (http://nces.ed.gov/das) or contact: Aurora D'AmicoPostsecondary Studies Division National Center for Education Statistics 1990 K Street, NW Washington, DC 20006 (202) 502-7334 Internet address: Aurora.D'Amico@ed.gov |
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