The median relative error is 0.73, meaning the median estimate was just 27% of the actual audience size. In other words,
the median participants underestimated their actual audience
size by a factor of four.
Participants in the general survey also underestimated their
audiences (Figure 1, right column). The median perceived
audience size in the general survey was 50 (mean = 137,
sd = 236), while the median actual audience (number of
friends who saw any post the user produced in the previous
month) was 180 (mean = 283, sd = 302). The median
relative error was 0.68, indicating that participants underestimated their general audience by roughly a factor of three.