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Experimental Research Methods (Fach) / L3 (Lektion)
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- Two sources of variation in the table •Mean differences betweengroups (“Systematic effect of groups?”) •Variation withingroups: “residual”, “natural variation independentof group membership” variation “due to collective effect of all other uncontrolled or extraneous variables”
- Explained Variance Scores between people vary, this variance is explained by the different experimental conditions
- unexplained variance all other unknown influences
- Residual how much person iin group kdeviates from its group mean
- Group effect ow much group kdeviates from the grand mean
- Population model The distance of the observed score from the population mean is explained by group-membership and a residual part
- Sample Estimates A person’s deviation score is decomposed in a part that is associated or predictable from group membership, and a residual part
- Total SS (SST) variation individualsw.r.t. grand mean
- Between SS (SSB) variation group meansw.r.t. grand mean
- Within or Residual SS (SSW) variation individualsw.r.t. group mean
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- ? group index
- ? number of groups
- ? person index
- nk #persons in group ?
- MSB measure of the dispersion of the group means
- ??W is the pooledestimate of the within-group variance; one value that applies to all groups