Posts organized by topic

Assessing Psyche, Engaging Gauss, Seeking Sophia

• Overture What this blog is about
• About me
• My academic webpage at Illinois State University
• My CV
• My software It is all free!

History of Psychological Assessment and Intelligence Research

• The impractical, intangible, invaluable consolations of studying old, outmoded theories My take on the value of studying the history of our field. Is this a 0, 1, or 2-point answer?
• Our debt to Francis Galton is great…and embarrassing. Intriguing and outrageous.
• Galton’s “ridiculous” intelligence tests More intrigue, less outrage.
• Francis Galton Reading Recommendations Brief reviews of some really interesting books. Why a mortified Galton apologized to Jane Austen’s family.
• Karl Pearson on why the idea of the correlation coefficient, not the formula, was the real breakthrough. Galton’s big idea is very big indeed.
• Charles Spearman Reading Recommendations Spearman…much more than g.
• “Strawman Spearman” vs. Charles Spearman Spearman was, and is, frequently misrepresented. I confess to having misstated a few things about Spearman myself.
• Cattell’s thoughts about Spearman. Cattell praises his mentor and relates a funny anecdote.
• After money, comfort, and love, Raymond Cattell had to make one more sacrifice… I, too, am grateful to the taxpayers of Illinois.
• Fun quote from Raymond Cattell on the importance of taxonomies Cattell’s influence was magnified by his ability to communicate with wit and charm.
• Leta Stetter Hollingworth (1886–1939) and sex differences in cognitive variability Solid research and marvelous prose from an intellectual giant.
• William Stern (1871–1938): The Individual Behind the Intelligence Quotient The guy who invented the much-maligned IQ actually agreed with IQ critics.
• Cronbach: Factor analysis is more like photography than chemistry. Before reading this old textbook I thought that it was just Meehl who was the wordsmith.
• Guttman’s Radex Model of Intelligence. A classic model with an updated 3D picture.

My thoughts on the theory and practice of psychological assessment

• What if we took our models seriously? Slides from my NASP 2014 talk The full text of the talk is in the “Notes” section.
• I am interviewed by the great Scott Barry Kaufman Intelligence is a folk concept and that’s a good thing. This and many other thoughts.
• Aptitudes and Achievement: Definitions, Distinctions, and Difficulties An excerpt from Principles of Assessment of Aptitude and Achievement.
• Potential Misconceptions about Potential Why it is common for a person’s achievement scores to be higher than aptitude scores?
• IQ Tests: Is Knowledge of Useless Knowledge Useless? In which I defend the use of knowledge tests.
• Why do IQ tests measure vocabulary? In which I defend the use of vocabulary in IQ tests and never once mention the word regatta.
• Explaining the difference between vision and visual-spatial processing to parents. Not an easy distinction!
• Needing Glasses for the Ears: Explaining Phonological Dyslexia to Parents This is my favorite thing to explain: It opens up new universes of understanding for parents.
• Two Kinds of Hierarchies in Cognitive Ability Models Why g and broad abilities are not necessarily causal entities.
• A Taxonomy of Influences on Ability Tests Not all error is specific.
• Within-Composite Differences: Why Measures of the Same Ability Differ More reasons than you ever thought you wanted to know.
• Do Large Subtest Differences Invalidate Composite Scores? Sometimes, but not usually.
• Why Specific Cognitive Processing Weaknesses Are Typically Only Partial Explanations for Academic Deficits It is hard to explain that which is mostly unexplained.
• Cognitive profiles are rarely flat. Two visualizations to train your intuition about how variable cognitive profiles are.

CHC Theory

• CHC Theory 2.0: Broad and Narrow Ability Definitions This list has been updated recently again by Kevin McGrew. CHC Theory 2.1?
• CHC Theory slides with simplified definitions. Feel free to download and use my PowerPoint Slides.
• CHC Theory: Love, Marriage, and a Giant Baby Carriage In which my inordinate fondness for extended metaphors gets the better of me.
• Cattell-Horn-Carroll (CHC) Theory of Cognitive Abilities in 3D? In which I take a good idea way too far.
• Carroll’s Three Stratum Theory of Cognitive Abilities, Re-Visualized Rethinking Carroll’s model leads to an alternate diagram.
• Extended Gf-Gc Theory, Visualized A re-imagined view of Horn’s model of intelligence.
• Fluid Intelligence, Defined My take on a concept that has been defined many times by many others.
• Crystallized Intelligence, Visualized The original image made for Schneider & McGrew (2012). The color and 3D effects had to be removed for the book chapter.
• Fluid and crystallized intelligence in the classroom and on the job. Some definitions, descriptions, and some slides.
• Where does Emotional Intelligence fit into CHC Theory? A new study on EI prompted me to make a video about the sorts of evidence that would be needed to amend CHC Theory.
• Exploratory model of cognitive predictors of academic skills that I presented at APA 2014. Why most realistic models are too complex to manage without software.
• Three inspired presentations at the Richard Woodcock Institute Event Three heavyweights in three rounds! Dick Woodcock delivered the body blows, Kevin McGrew took care of the head shots, and Cathy Fiorello knocked us out.

Specific batteries and tests

• WAIS-IV & WIAT-III Multidimensional Scaling in 3D Rotate it in 3D! Zoom in and out! Hours of entertainment!
• Interactive 3D Multidimensional Scaling of the WJ III Gc and Grw are densely packed!
• Interactive 3D Multidimensional Scaling of the WISC-IV What is Cancellation doing way out there?
• Do CAS Planning Subtests Measure Planning or Processing Speed? Or both?
• Correlation Matrices from Five Cognitive Ability Tests, Visualized In which you can see that the SB5 is quite different from the others.
• g Factor Removed from Correlation Matrices, Vizualized In which you can REALLY see that the SB5 is different from the others.
• Factor Analysis of the WISC-IV Integrated with a Schmid-Leiman Transformation With pretty pictures!
• No, the WISC-IV doesn’t underestimate the intelligence of children with autism. A review of paper that contains a misunderstanding of the purpose of cognitive ability tests.
• Is the structure of intelligence different for people with learning disorders? Let’s hope so! A post-publication review of a study with flawed methods.
• WISC-V Expanded Composite Scores A welcome addition to the WISC-V

Death Penalty & IQ

• IQ, the death penalty, and me I am honored to have my work cited in a recent U.S. Supreme Court decision. Special thanks to Cecil Reynolds and Kevin McGrew.
• Why averaging multiple IQ scores is incorrect in death penalty cases The averaged score has the wrong standard deviation and should be re-scaled.
• Execution by Miscalculation Some people might be executed because their IQ was improperly estimated.
• Can’t Decide Which IQ Is Best? Make a Composite IQ Score I rewrote a section from my 2013 chapter in the Oxford handbook of psychological assessment of children and adolescents to make its application to death penalty cases very clear.

ADHD

• What role should cognitive tests of attention play in ADHD diagnosis? A short blunt answer—followed by a qualification, a diagram, and an extended elaboration.
• Attention Tests and ADHD A modest proposal.

The g factor

• Is g an ability? Spearman didn’t think so.
• Mean-spirited Mono-g-ists vs. Muddleheaded Poly-G-ists If only the rocks in the heads of former could fill the holes in the heads of the latter!
• The rise and fall of g and the end of bigotry I’ve always found the notion research affects that bigots’ opinions rather charming.

Psychological Evaluation Report Writing

• Advice for psychological evaluation reports: Make every sentence worth reading Removing clutter gets you half the way there!
• Advice for psychological evaluation reports: Write about people, not tests A comparison of two styles of report-writing.
• Advice for psychological evaluation reports: Render abstruse jargon in the vernacular Dispelling the two-way illusion that someone knows what is going on.
• My Template for Psychological Evaluation Reports Using MS Word’s Styles makes quick within-report navigation a real time-saver.
• MS Word Trick: Make your headings stay on the same page as the paragraph below This trick makes editing your reports a little less burdensome.
• Communicate with percentile ranks…but think and reason with standard scores Thinking in percentiles is like counting on your figures. With explanatory graph.
• Standard Scores in Psychological Evaluation Reports An accurately drawn normal curve with index scores, T scores, scaled scores, and percentiles.
• Allowing yourself to be wrong allows you to be right…eventually Our dangerous capacity to make sense of nonsense.
• Dr. Procrustes does not need to see you; he has your test scores. Why by-the-book interpretations of test scores is sometimes a bad idea.
• Time lavished on hypothesis fishing trips is stolen from children we no longer have time to help. Why sometimes you should stop testing even though the question can be answered.

Recommended Blogs & Interesting Studies

• No, the WISC-IV doesn’t underestimate the intelligence of children with autism. Just because people with autism score lower on a test does not mean that we should stop using it.
• Intelligence and the Modern World of Work: A Special Issue of Human Resource Management Review. I/O psychologists to collaborate with scholars from other disciplines to explore how advances in intelligence research might be incorporated into our understanding of the role of intelligence in the workplace.
• John Willis’ Comments on Reports newsletter makes me happy. Every time there is a new edition, I feel the way I imagine teenagers felt in 1964 when the Beatles released another single.
• Beyond IQ, a new blog about psychological assessment Smadar Sapir Yogev, an educational psychologist working in Jerusalem, posts great presentations in both Hebrew and in English on a wide range of assessment-related topics. It took me a while to figure out that her PowerPoint slides advance using the “left” arrow.
• New Favorite Blog: blog de Roberto Colom. If you read Spanish, you should be following this blog. If you don’t, you should be following this blog.
• James Thompson on “Alternate Intelligences” Thompson’s critique of Keith Stanovich’s critique of IQ tests.
• Spatial memory and fluid intelligence: A small question answered very well An example of cognitive ability research that I admire.
• Working memory capacity for body movements? A novel working memory capacity test with evidence for differential predictive validity.
• Short list of bad things associated with high IQ This was my most-viewed post ever. There is a market for bad news about IQ!
• Fluctuations in attention are related to fluid but not crystallized intelligence. A brief summary of what I consider to be an important new paper by Unsworth and McMillan (2014).
• Undiscovered Math Math with Bad Drawings is brilliant!
• Why do IQ scores predict job performance? High scorers get more job-specific training.
• Beautiful Hypotheses and Ugly Facts about Phonological Processing Deficits and Reading Things are more complicated than you might think!
• Good News for People Planning to Get Old Cognitive declines are getting less steep.
• The Correlation between Simple and Complex Memory Span Tests Increases with Age in Children and Adolescents The hypothesized reason for the increased correlation is interesting.
• Good News for Soccer Players? A little bit of heading perhaps not so bad for your head.
• Meta-analysis confirms association between premorbid IQ loss and schizophrenia onset Even so, most people in whom IQ drops never experience schizophrenia.
• Living in a moldy house is bad for your baby’s brain. We already knew this but now we are more certain.
• Delightful article about cloze tests? Yes, delightful I say!
• Nice summary of phenotypic hallmarks of learning disorders

Psychometrics & Statistics

• Viewing correlation from a different angle More crazy animations! With a brief visual explanation of the Mahalanobis distance (a measure of how unusual a profile is).
• Visualizing covariance It was this visualization that made me feel like I finally grokked covariance.
• A Gentle, Non-Technical Introduction to Factor Analysis I promise that it won’t hurt!
• Reliability coefficients are for squares. Confidence interval widths tell it to you straight. I have no gut-level sense of what a 0.70 reliability coefficient means. I bet you don’t either.
• Reliability is where the light is. Validity is where the keys are. A reference to an old joke that is annoyingly useful.
• Unfortunate statistical terms Technical terms I wish weren’t misleading.
• Two visualizations for explaining “variance explained” My attempt to “unmislead” people misled by a misleading term.

Regression and Multiple Regression

• Simple Regression Tutorial Using Prezi My first Prezi. It sorta makes me dizzy!
• Predicted Achievement Using Simple Linear Regression A brief tutorial.
• Misunderstanding Regression to the Mean A video tutorial about common misunderstandings about regression to the mean. There are examples specific to death penalty cases in the tutorial.
• Conditional normal distributions provide useful information in psychological assessment. A rotating 3D image, a tutorial with scary math, some static images, a useful spreadsheet, and a video explaining how to use the spreadsheet. The spreadsheet allows you to answer questions like, “Among people who score 120 on vocabulary and 80 on working memory, what proportion score 90 or less on reading comprehension?”
• 3D Multiple Regression Graph Using the rgl Package in R.

The Glories of R!

• Bifactor Model in 3D When 2 dimensions just isn’t enough!
• I love the animation package in R! Trying to make statistics a little less boring…one animated graphic at a time.
• Excel Macro for Making Matrices in R I made this mainly for me but you might find it useful.
• Keeping beautiful R graphs beautiful in PowerPoint Inkscape is your friend!

Normal and Multivariate Normal Distributions

• Conditional normal distributions provide useful information in psychological assessment. A rotating 3D image, a tutorial with scary math, some static images, a useful spreadsheet, and a video explaining how to use the spreadsheet. The spreadsheet allows you to answer questions like, “Among people who score 120 on vocabulary and 80 on working memory, what proportion score 90 or less on reading comprehension?”
• Using the truncated normal distribution Answer questions like “Among people with IQs over 130, what percent have IQs over 145?”
• Using the multivariate truncated normal distribution Answer questions like “Among people with IQs less than 70, what percent have reading comprehension scores greater than 85?”
• How unusual is it to have multiple scores below a threshold? A method for estimating the prevalence of low scores in a particular battery of tests.
• How common is it to have no academic weaknesses? What if we know the person’s cognitive profile? How common is it to have no academic weaknesses then?
• Difference scores, the absolute deviation, and the half-normal distribution A way to talk about difference scores that is both accurate and easy to explain.

Composite Scores

• Real Composite Scores vs. Averaged Pseudo-Composite Scores A non-peer-reviewed review written with my peer, the peerless Kevin McGrew.
• Why composite scores are more extreme than the average of their parts With crazy animations of rotating axes!
• Can’t Decide Which IQ Is Best? Make a Composite Score. What if a person has IQ scores both above and below a threshold for obtaining services?
• A Geometric Representation of Composite Scores With video explanation.

Psychometrics from the Ground Up: A Series of Video Tutorials

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

Software

• TableMaker A program for making tables in psychological reports.
• The Compositator Supplementary software for the WJ III.
• An easy way to simulate data according to a specific structural model. An Excel spreadsheet with a video explaining how to use it.
• What if We Took Our Models Seriously? Estimating Latent Scores in Individuals Spreadsheets for the WISC-IV and WAIS-IV that calculate latent score estimates with appropriate confidence intervals