In-class exercise on Population distributions, sampling distributions, and
confidence intervals
Each student surveys (at random) eight classmates for their shoe size (If you
are uncomfortable revealing the truth, then lie.)
Calculate the average of the first 4 people surveyed.
Calculate the average of the first 8 people surveyed.
Report to the professor
a. Your shoe size
b. n=4 average
c. n=8 average
We should observe that the population is not normal
The sampling distribution n=4 is close to normal
the sampling distribution is even closer to normal
The standard error for the sampling distributions (the standard deviation of
the sample averages) is approximately the pop stdev /sqrt(n).