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Bal23
Lapis Lazuli | Level 10

I previously used regression analysis and there is a significant difference. Then I realize my dependent variable is not normally distirbuted, it is very skewed.

So I use proc genmod. Anyother analysises, please give advice.

below is the error message

 

1523 proc genmod data = have;

1524 model abb= mbb /dist=negbin;

1525 run;

NOTE: Non-integer response values have been detected for the

Negative Binomial distribution.

WARNING: No output destinations active.

NOTE: Algorithm converged.

NOTE: The negative binomial dispersion parameter was estimated

by maximum likelihood.

NOTE: PROCEDURE GENMOD used (Total

7 REPLIES 7
PGStats
Opal | Level 21

"dist=negbin" requests maximum likelihood parameter estimation to explain things that can be counted. Counts are integers. What is abb?

PG
Bal23
Lapis Lazuli | Level 10

abb is my dependent variable, mbb is my independent variable

Tom
Super User Tom
Super User

@Bal23 wrote:

abb is my dependent variable, mbb is my independent variable


The questions was meant to be what type of values does ABB contain, not its role in your model.

 

Are they positive integer values? If not then it is not appropriate to assume it should follow a negative binomial distribution.

PGStats
Opal | Level 21

Advice: Take an Introductory course in Probability. Learn the difference between discrete and continuous distributions. 

PG
ClaudiaJimenezC
Calcite | Level 5

This comment is unnecessarily rude, PGStats.

ballardw
Super User

You didn't mention which type of regression you initially performed. Many types do not require the data to be normally distributed but that the errors are normally distributed.

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