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PEDAR: Research Methodology  The Road Lsss Traveled? Students Who Enroll in Multiple Institutions
Introduction
Beginning Postsecondary Students Longitudinal Study
The 2001 Baccalaureate and Beyond Longitudinal Study
Accuracy of Estimates
Item Response Rates
Data Analaysis System
Statistical Procedures
Differences Between Means
Linear Trends
Multivariate Commonality Analysis
Missing Data and Adjusting for Complex Sampling Design
Interpreting the Results
Executive Summary
References
Full Report (PDF)
Executive Summary (PDF)
 Data Analaysis System

The estimates presented in this report were produced using the Data Analysis System (DAS) for each of the surveys analyzed. 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 errors5 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 surveys.

The DAS can be accessed electronically at http://nces.ed.gov/das. For more information about the Data Analysis System, contact:

Aurora D'Amico
Postsecondary Studies Division
National Center for Education Statistics
1990 K Street, NW
Washington, DC 20006-5652
(202) 502-7334
aurora.d'amico@ed.gov

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National Center for Education Statistics - http://nces.ed.gov
U.S. Department of Education