1. Two Crossed Random Factors
David A. Kenny

2. *
Background
Multilevel Modeling
Nested *

3. *
Data Structure
There are two level 2 variables that have a crossed, not a nested, structure.
Examples
Participants and stimuli
Participants and situations
Participants and items *

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Illustration
Study 1 from Smith–McLallen, A., Johnson, B. T., Dovidio, J. F., & Pearson, A. R. (2006). Implicit color and race preferences black and white: The role of color bias in implicit race bias. Social Cognition, 24, *

5. Download
Data
Syntax
Output

6. Details 67 participants non-white participants excluded*
Details
67 participants
non-white participants excluded
one participant with more than 20% errors excluded
12 faces, 6 white and 6 black
Implicit Attitude Test (IAT) Study *

7. Variables Face Participant (part) Race nested within Face*
Variables
Face
Participant (part)
Race nested within Face
+1 White Face
-1 Black Face
Positivity
Reaction times in milliseconds to each face when paired with a negative word minus when paired with a positive word.
Larger numbers, more positive toward the face. *

9. Syntax MIXED positivity WITH race /FIXED = race*
Syntax
MIXED
positivity WITH race
/FIXED = race
/PRINT = SOLUTION TESTCOV
/RANDOM INTERCEPT | SUBJECT(face)
/RANDOM INTERCEPT race | SUBJECT(part) COVTYPE(UN).
Note that residual is the part x face interaction. *

15. White Faces
Black Faces

16. Only variance that is statistically significant (p =
Only variance that is statistically significant (p = .0185) is race of face effect for participants. Some participants show more bias than do others. About 89% of the variance is due to error, 1% due to participant differences, and 9% due to race bias differences due to participant.
The race effect is ± Given a normal distribution of the race effect for participants, approximately 95% of whites show a bias in favor of whites.

17. Thank You! Aaron Smith-McLallen*
Thank You! Aaron Smith-McLallen *

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Other Webinars
References (pdf)
Advanced Topics *