Most estimates presented in this report were produced using the NSOPF:99 Data Analysis Systems (DAS). The DAS software makes it possible for users to specify and generate their own tables from the NSOPF:99 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 errors⁵ and weighted sample sizes for these estimates. For example, table B1 contains standard errors that correspond to table 2 in this report, and was generated by the DAS. 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.