Simplified Edition · Module 05
Personality & Individual Differences
Traits, structure and measurement: what a score supports, and what it cannot be asked to carry.
- 18 activities
- 5 to 7 minutes each
- 108 minutes end to end
The activities
In teaching order
-
How Much Room Does the Situation Leave?
Why the same people look alike in one setting and quite different in another
5 min
-
One Moment, or the Whole Fortnight?
Why one observation cannot tell you what somebody is generally like
6 min
-
Turn the Axes, Change Every Number
What rotation changes in a factor analysis, and what it cannot change
6 min
-
Same Score, Different People
What a broad trait score averages away, and why the tie depended on the questionnaire
6 min
-
Chasing Alpha
Why a high Cronbach's alpha is not evidence that a scale is any good
6 min
-
Reverse-Item Disaster
Reverse keying, and what an unrecoded item does to a scale's reliability statistics
5 min
-
Four Ways to Answer the Same Questionnaire
What reverse-worded items fix, and what they leave exactly as they were
6 min
-
The Same Difference, Twice Over
Why a group difference in scores is not yet a group difference in the trait
6 min
-
Five Explanations, All of Them Fit
Why an explanation that fits everything has told you nothing
6 min
-
No Best Battery
Why a test battery cannot be good or bad until you say what it is for
7 min
-
A General Factor With No General Ability
Why every cognitive test correlating with every other proves less than it seems
6 min
-
Take the Words Out and See What Is Left
Why a test with no words in it still assumes a great deal
7 min
-
Equally Accurate, or Equally Fast
Why a score and a reaction time have to be read together or not at all
5 min
-
The Same Genes, A Different Heritability
Why heritability is a fact about a population and not about a person
6 min
-
Three Findings, Two Lines
Why the same interaction supports three different theories depending on where you looked
6 min
-
It Correlates. So What?
Why a measure correlating with an outcome does not mean it is worth having
6 min
-
Same Average, Six Very Different Weeks
The four things a single self-esteem score collapses into one
6 min
-
Where the Line Goes
What changes when a continuum is cut into a category, and who decides
7 min
Elsewhere
Every activity here has a full-length twin in the main collection, linked from the foot of the activity itself.