Cognitive Assessment, Death Penalty, Psychometrics, Statistics, Tutorial, Uncategorized, Video

Video Tutorial: Misunderstanding Regression to the Mean

One of the most widely misunderstood statistical concepts is regression to the mean. In this video tutorial, I address common false beliefs about regression to the mean and answer the following questions:

  1. What is regression to the mean?
  2. Do variables become less variable each time they are measured?
  3. Does regression to the mean happen all the time or just in certain situations?
  4. Does repeated testing cause people to come closer and closer to the mean?
  5. How is regression to the mean relevant in death penalty cases?

Cognitive Assessment, My Software & Spreadsheets, Psychometrics, Tutorial, Uncategorized, Video

Estimating Latent Scores in Individuals

How to estimate latent scores in individuals when there is a known structural model:

I wrote a commentary in a special issue of the Journal Psychoeducational Assessment. My article proposes a new way to interpret cognitive profiles. The basic idea is to use the best available latent variable model of the tests and then estimate an individual’s latent scores (with confidence intervals around those estimates). I have made two spreadsheets available, one for the WISC-IV and one for the WAIS-IV.

Five-Factor Model of the WISC-IV

Four-Factor Model of the WAIS-IV

I decided not to provide a spreadsheet for the five-factor model of the WAIS-IV because Gf and g were so highly correlated in that model that it would be nearly impossible to distinguish between Gf and g in individuals. You can think of Gf and g as nearly synonymous (at the latent level).

Schneider, W. J. (2013). What if we took our models seriously? Estimating latent scores in individuals. Journal of Psychoeducational Assessment, 31, 186–201.

Cognitive Assessment, My Software & Spreadsheets, Psychometrics, Psychometrics from the Ground Up, Tutorial, Uncategorized, Video

Psychometrics from the Ground Up 9: Standard Scores and Why We Need Them

In this video tutorial, I explain why we have standard scores, why there are so many different kinds of standard scores, and how to convert between any two types of standard scores.

Here is my Excel spreadsheet that converts any type of standard score to any other type.