Not surprisingly, estimates of audience size “in general” were
significantly larger than those for a specific post in the past
(mean = 137 vs. 60, p < 0.001). As disjoint sets of friends
may see different pieces of content, it makes sense that in a
month, more people would see a given user’s content than
would see any single post she made. Survey participants correctly accounted for this.
To further quantify this relationship, we can fit a linear model
to measure the correlation between estimated and actual audience size. The model does not explain much variance at all:
R
2
= 0.04, p < .001.