Version info: Code for this page was tested in Stata 12. Negative binomial regression is for modeling count variables, usually for over-dispersed count outcome variables. Please note: The purpose of…
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Version info: Code for this page was tested in Stata 12. Examples of ordered logistic regression Example 1:  A marketing research firm wants to investigate what factors influence the size…
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Version info: Code for this page was tested in Stata 12. Poisson regression is used to model count variables. Please note: The purpose of this page is to show how…
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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…
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Version info: Code for this page was tested in Stata 12. Probit regression, also called a probit model, is used to model dichotomous or binary outcome variables. In the probit…
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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…
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Version info: Code for this page was tested in Stata 12. Robust regression is an alternative to least squares regression when  data is contaminated with outliers or influential observations and…
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Examples Example 1. A company that manufactures light bulbs claims that a particular type of light bulb will last 850 hours on average with standard deviation of 50. A consumer…
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Examples Example 1. A clinical dietician wants to compare two different diets, A and B, for diabetic patients. She hypothesizes that diet A (Group 1) will be better than diet…
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Examples Example 1. A company markets an eight week long weight loss program and claims that at the end of the program on average a participant will have lost 5…
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