Pygmalion Effect
One company of soldiers in each of 10 platoons was assigned to a Pygmalion treatment group, with remaining companies in the platoon assigned to a control group. Leaders of the Pygmalion platoons were told their soldiers had done particularly well on a battery of tests which were, in fact, non-existent. In this randomised block experiment, platoons are experimental units, companies are blocks, and average Practical Specialty test score for soldiers in a platoon is the response. The researchers wished to see if the platoon response was affected by the artificially-induced expectations of the platoon leader.
case1302
A data frame with 29 observations on the following 3 variables.
Companya factor indicating company identification,
with levels "C1", "C2", ..., "C10"
Treata factor indicating treatment with two levels,
"Pygmalion" and "Control"
Scoreaverage score on practical specialty test of all soldiers in the platoon
Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.
Eden, D. (1990). Pygmalion Without Interpersonal Contrast Effects: Whole Groups Gain from Raising Manager Expectations, Journal of Applied Psychology 75(4): 395–398.
str(case1302) # two-way model with interactions fitfull <- aov(Score ~ Company*Treat, case1302) # No problems are indicated by residual plot plot(fitfull) # Interaction terms are not statistically significant anova(fitfull) # Additive model, with "treatment contrast" for treatment: fitadditive <- aov(Score ~ Company + Treat, case1302) # Interpret treatment effect as coefficient of Treat anova(fitadditive)
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