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In this video I will answer a question from a recent webinar Random Intercept and Random Slope Models.

We are answering questions here because we had over 500 people live on the webinar so we didn’t have time to get through all the questions.

If you missed the webinar live, this and the other questions in this video series may make more sense if you watch that first. It was part of our free webinar series, The Craft of Statistical Analysis, and you can sign up to get the free recording, handout, and data set at this link:

http://TheCraftofStatisticalAnalysis.com/random-intercept-random-slope-models

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In this video I will answer a question from a recent webinar Random Intercept and Random Slope Models.

We are answering questions here because we had over 500 people live on the webinar so we didn’t have time to get through all the questions.

If you missed the webinar live, this and the other questions in this series may make more sense if you watch that first. It was part of our free webinar series, The Craft of Statistical Analysis, and you can sign up to get the free recording, handout, and data set at this link:

http://TheCraftofStatisticalAnalysis.com/random-intercept-random-slope-models

No comments yet

Pretty much all of the common statistical models we use, with the exception of OLS Linear Models, use Maximum Likelihood estimation.

This includes favorites like:

• All Generalized Linear Models, including logistic, probit, beta, Poisson, negative binomial regression
• Linear Mixed Models
• Generalized Linear Mixed Models
• Parametric Survival Analysis models, like Weibull models
• Structural Equation Models

That’s a lot of models.

If you’ve ever learned any of these, you’ve heard that some of the statistics that compare model fit in competing models require (more…)

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One of the most common—and one of the trickiest—challenges in data analysis is deciding how to include multiple predictors in a model, especially when they’re related to each other.

Let’s say you are interested in studying the relationship between work spillover into personal time as a predictor of job burnout.

You have 5 categorical yes/no variables that indicate whether a particular symptom of work spillover is present (see below).

While you could use each individual variable, you’re not really interested if one in particular is related to the outcome. Perhaps it’s not really each symptom that’s important, but the idea that spillover is happening.

(more…)

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One question that seems to come up pretty often is:

Well, let’s start with how they’re the same:

Both are types of generalized linear models. This means they have this form:

(more…)

18 comments

Here’s a common situation.

Your grant application or committee requires sample size estimates.  It’s not the calculations that are hard (though they can be), it’s getting the information to fill into the calculations.

Every article you read on it says you need to either use pilot data or another similar study as a basis for the values to enter into the software.

You have neither.

No similar studies have ever used the scale you’re using for the dependent variable.

And while you’d love to run a pilot study, it’s just not possible.  There are too many practical constraints — time, money, distance, ethics.

What do you do?

(more…)

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