The data comes from a study titled, Behavioral Appropriateness and Situational Constraint as Dimensions of Social Behavior, published in the Journal of Personality and Social Psychology. In the paper 52 subjects were asked to keep diaries for a short period after which Behaviors and Situations were aggregated from the diaries. From this 15 Behaviors and 15 Situations were derived resulting in 225 possible pairings of Behaviors with Situations (15*15 = 225). Then the subjects were shown individual pairings (in a fixed random order) and asked to rate their appropriateness on a scale from 0 to 9 (10-point scale). Afterwards the results were tabulated and a mean was computed for each pair thus resulting in a 15 by 15 matrix of mean appropriateness ratings of behaviors in situations.
The paper goes on to have some discussion about the meaning of the results and what it may mean to average out a behavior across all of its situations (and vice versa).
I suspect that subjects were