**A series of video tutorials** by W. Joel Schneider

1. Variables and Measurement Scales

2. Frequency Distributions

3. Probability Density Functions

4. Expected Value: What Does the Mean Mean?

5. Expected Value and Variance: Take a Moment or Two to Find Out How the Mean and Variance Are Alike

6. The Normal Distribution and the Central Limit Theorem: Sum of the Many Reasons Variables Are Normally Normal

7. Skewness: Lopsided Variability

8. Kurtosis: Beyond Peakedness

9. Standard Scores and Why We Need Them

10. Covariance

**Additional Videos**

Two Kinds of Hierarchies in Cognitive Ability Models

A Taxonomy of Influences on Ability Tests

Within-Composite Differences: Why Measures of the Same Ability Differ

Do Large Subtest Differences Invalidate Composite Scores?

A Geometric Representation of Composite Scores

What if We Took Our Models Seriously? Estimating Latent Scores in Individuals

Misunderstanding Regression to the Mean

Contact Me: Joel Schneider wjschne@ilstu.edu

Excellent explanations, even for a marginally statistically literate person, like me.

Best wishes, Ruben, Moreno Valley Unified School District,CA

Thanks Ruben!

One of the reasons that I am doing this is to become less marginally literate myself.

Joel, I agree with Ruben. If I weren’t so grateful I’d be downright embarrassed (and who knew there were two ‘r’s in embarrassed? thank goodness for spellcheck!). Seriously, you are providing a terrific service and I am very grateful.

Best,

Tom

Thanks Tom!

A stress-saver. I was scratching my head and saying “oh, no …” to myself over 2 clients with very low academic skills despite mid-average intelligence and a cognitive processing factor about 20th %ile. Your video showed me that such factors don’t have the ‘power’ I assumed they had, as even one at 5th %ile can’t be assumed to have explanatory value. Thanks for this information.

Shocking, isn’t it? It went against all my intuitions. Glad to be of help.