I recently received this interesting question regarding Multilevel Models after one of my last blog posts: Question: Can you tell me when a multilevel-model is not appropriate? I have data that by design is clustered but the random intercept in the nul...

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Tags: multilevel models, statistical training, Uncategorized

Posted in SAS | Comments Off on When is a Multilevel Model not appropriate?

Multilevel models (also called hierarchical linear models) are used to analyze clustered or grouped data, as well as longitudinal or repeated measures data. Consider the simple scenario shown below, where Y is continuous and is shown as a function of a...

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Tags: multilevel models, statistical training, Uncategorized

Posted in SAS | Comments Off on Multilevel Models Part 2: What is a Multilevel Model?

If you have data where the observations are not independent due to nesting or clustering, you may need a multilevel model. Another scenario that would require a multilevel model is if you have data where observations have been gathered multiple times o...

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Tags: multilevel models, statistical training, Uncategorized

Posted in SAS | Comments Off on Multilevel Models Part 1: Do I Need a Multilevel Model?

FINALLY…the simplest ESTIMATE statements to write are for continuous variables not involved in interactions or higher order terms. Consider a data set containing the 2004 SAT scores for each of the 50 states. The file includes the combined math and v...

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Tags: contrast, estimate statement, regression model, statistical training, Uncategorized

Posted in SAS | Comments Off on ESTIMATE Statements – the final installment

My previous blog demonstrated the most difficult type of ESTIMATE statement to write—a two-way (or higher) ANOVA with interactions. An "easy button" for ESTIMATE statement comes by having a simpler model. Models with only main effects and no interact...

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Tags: comparisons, contrast, estimate statement, statistical training, Uncategorized

Posted in SAS | Comments Off on "Easy button" for ESTIMATE statements

When asked to select the best (or worst) of something in a business setting, do you wish you had "magic glasses" to see the answer? PROC GLM and other statistical modeling procedures have their own versions of such an item with their ESTIMATE (and CONT...

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Tags: comparisons, estimate statement, statistical training, Uncategorized

Posted in SAS | Comments Off on The magical ESTIMATE (and CONTRAST) statements

When you think of statistical process control, or SPC for short, what industry first comes to your mind? In the past 10 or 15 years, diverse industries have begun to standardize processes and administrative tasks with statistical process control. ...

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Tags: Cat Truxillo, data analysis, exchanging ideas, SAS, statistical training

Posted in SAS | Comments Off on The Human Side of Statistical Process Control: Three Applications of SAS/QC You Might Not Have Thought About

Lunch. For some workers, it’s the sweetest part of an otherwise bitter day at the grindstone. Nothing can turn that sweetness sour like going into the breakroom to discover that someone has taken your lunch and eaten it themselves.
Nothing lik...

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Tags: Cat Truxillo, data analysis, SAS, statistical training, tips and tricks

Posted in SAS | Comments Off on Who Ate My Lunch? Discriminant Thresholds to Reduce False Accusations