Version info: Code for this page was tested in SAS 9.3. Examples of ordered logistic regression Example 1:  A marketing research firm wants to investigate what factors influence the size…
Read More

Poisson regression is for modeling count variables. Please note: The purpose of this page is to show how to use various data analysis commands.  It does not cover all aspects…
Read More

Introduction Power analysis is the name given to the process for determining the sample size for a research study. The technical definition of power is that it is the probability…
Read More

Robust regression is an alternative to least squares regression when  data is contaminated with outliers or influential observations and it can also be used for the purpose of detecting influential…
Read More

Note: This page uses SAS 9.2. The tobit model, also called a censored regression model, is designed to estimate linear relationships between variables when there is either left- or right-censoring…
Read More

Zero-inflated negative binomial regression is for modeling count variables with excessive zeros and it is usually for over-dispersed count outcome variables. Furthermore, theory suggests that the excess zeros are generated…
Read More

Version info: Code for this page was tested in SAS 9.3 Zero-inflated Poisson regression is used to model count data that has an excess of zero counts. Further, theory suggests…
Read More

Version info: Code for this page was tested in SAS 9.3. Zero-truncated negative binomial regression is used to model count data for which the value zero cannot occur and when…
Read More

Version info: Code for this page was tested in SAS 9.3 Zero-truncated poisson regression is used to model count data for which the value zero cannot occur. Please Note: The…
Read More

Note: This page is designed to show the how multilevel model can be done using R and to be able to compare the results with those in the book. On…
Read More