A Researcher Reports That the Effectiveness of a New Marketing $\eta$

Multiple Choice

A researcher reports that the effectiveness of a new marketing campaign significantly increased sales compared with the previous campaign strategy,t(49) = 2.562,p < .05.Use $\eta$ ² to interpret the effect size for this result.

A) 12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy.
B) 12% of the standard error can be accounted for by the effectiveness of the marketing strategy.
C) Marketing effectiveness shifted 0.12 standard deviations above the mean in the population.
D) 12% of the variability in marketing effectiveness can be accounted for by the new marketing strategy and 12% of the standard error can be accounted for by the effectiveness of the marketing strategy.