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Statistical Material for Download

This page contains links to statistical programs and materials developed by the Biostatistics Center faculty and staff. All such programs are copyrighted by the authors. The authors do not guarantee the accuracy of the methods or the programs. These programs are free software; you can redistribute them and/or modify them under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License or any later version. This software is provided "AS IS" without warranty of any kind. The entire risk as to the quality and performance of the software is with you. Please see the GNU license text for details.

  • Wei and Lachin Multivariate Rank Analysis. Multivariate Rank Analysis. This is a SAS macro to implement the original Wei and Lachin (1984) multivariate Mann-Whitney analysis. The Macro also provides a number of different test statistics as described in Lachin (1992). Download. In August 2013 a minor discrepancy was detected between the program documentation and descriptions and how the output of the Mann-Whitney analysis was labeled. See the document readme.doc. The program was revised to correspond with the documentation.
    • Wei LJ and Lachin JM. Two-sample asymptotically distribution-free tests for incomplete multivariate observations. Journal of the American Statistical Association, 1984, 79, 653-661.

    • Thall PF and Lachin JM. Analysis of recurrent events: Nonparametric methods for random interval count data. Journal of the American Statistical Association, 1988, 83, 339-347.

    • Lachin JM. Some large sample distribution-free estimators and tests for multivariate partially incomplete data from two populations. Statistics in Medicine, 11, 1151-1170, 1992.

  • Futility Assessment Based on Conditional Power. These are SAS programs to compute the properties of a futility assessment based on a conditional power computation as described in Lachin (2005). Download
    • Lachin JM. A review of methods for futility stopping based on conditional power. Statistics in Medicine, 24, 2747-2764, 2005.

  • Futility Assessment Based on Interim Z-test Values. These are SAS programs to implement a futility assessment based on a boundary on the interim Z-test value or a confidence limit as described in Lachin (2009). This does not require specification of a boundary on a conditional power value although the corresponding conditional power value is readily obtained. Download
    • Lachin JM. Futility interim monitoring with control of type I and II error probabilities using the interim Z-value or confidence limit. Clinical Trials, 2009, 6:565-573.

  • Parametric Survival Models For Interval Censored Data With Time-Dependent Covariates. This SAS program fits parametric regression model to interval censored event-time data with allowance for time-dependent covariates. The SAS macro and documentation are provided. Download programs, documentation, and SAS data set here.

  • Robust Estimating Equations (REE). This SAS Macro implements robust estimating equations for analyzing longitudinal data based on the methods developed by Hu and Lachin (2001). It includes GEE as a special option. The Levenberg-Marquardt algorithm has been used to improve convergence rates. This macro employs the same platform as the GEE macro developed by Ulrike Groemping (1993). The SAS macro and documentation are provided. Download
    • Hu M and Lachin JM. Application of robust estimating equations to the analysis of quantitative longitudinal data, Statistics in Medicine, 20, 411-3428, 2001.

  • Sample Size and Power for a Logrank Test and Cox Proportional Hazards Model with Multiple Groups and Strata, or a Quantitative Covariate with Multiple Strata. These are the SAS programs that performed the various computations presented in the Example section as described in Lachin (2013): Download.
  • Reference:
    • Lachin JM. Sample size and power for a logrank test and Cox proportional hazards model with multiple groups and strata, or a quantitative covariate with multiple strata. Statistics in Medicine 2013; 32:4413-4425. DOI: 10.1002/sim.5839.

  • Data Analysis Plan and Data Analysis Policy. An outline of a data analysis plan that can be modified and adapted for individual use is given here: Download. An example of Data Analysis Policy is available here: Download.
    • Best Practice: The Data Analysis Plan ? A Blueprint for Success. The American Statistical Association Conference on Statistical Practice February 20, 2015, New Orleans.
  • Optimal Screening Schedules For Disease Progression, With Application to Diabetic Retinopathy. This is a technical report describing the statistical models employed for the net-benefit analysis in Nathan et al. (2016). Download, R code Download.
    • Nathan DM, Bebu I, Hainsworth D, Klein R, Tamborlane W, Lorenzi G, Gubitosi-Klug R, Lachin JM. Establishing Rational individualized Screening Guidelines for Retinopathy in Type 1 Diabetes, submitted for publication, 2016.