Eighty subjects estimated the correlation coefficient,
r, for each of 13 computer-printed
Making judgments were 46 students in a
graduate-level statistics course and 34 faculty and
graduate students in a department of psychology.
The actual correlation values ranged from .010 to
.995, with 200 observations in each scatterplot and
with the order of scatterplot presentation randomized.
As predicted, subjects underestimated the
degree of actual correlation. Also as predicted, but
with substantial moderation by a method-of-presentation
factor, this underestimation was most pronounced
in the middle of the correlational
range-between the 0 and 1 extremes. Though perception
of correlation was shown not to be veridical
(i.e., in terms of r), little support was given one alternative
view-its being in terms of r².