But there are many design issues that affect power in a study that go way beyond a z-test. Like:
repeated measures
clustering of individuals
blocking
including covariates in a model
Regular sample size software can accommodate some of these issues, but not all. And there is just something wonderful about finding a tool that does just what you need it to.
Especially when it’s free.
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Factor is tricky much in the same way as hierarchical and beta, because it too has different meanings in different contexts. Factor might be a little worse, though, because its meanings are related.
In both meanings, a factor is a variable. But a factor has a completely different meaning and implications for use in two different contexts.
Factor analysis
In factor analysis, a factor is an unmeasured, latent variable, that expresses itself through its relationship with other measured variables.
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