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Logistic regression sub-group size parameters
Someone in my lab has a sample of 500 older kids and he wants to investigate what factors are related to the probability that they will bully. Groups:
- kids were bullied and go on to bully is made up of 22;
- were not bullied but go on to bully is made up of 28 kids;
- never bullied and never bully is made up of 250;
- were bullied and never bully is made up of 200.
They created an interaction variable using age*not bullied/bullied and added 14 other "predictors" to the mode. Interaction of age and bullying is sig but the prototypical plot looks weird, the group who were bullied have a 0 slope by age and the line starts and ends at 0. My guess is the the bullied/bullying group is way too small for all the info in the model. IF so, what are the group size parameters or ratio to total group parameters for logistic regression? Thank you very much!
