Reading Notes: Module 4 STAT 212
Sect. 4.3: We only cover part of this section, starting out at “The mean of a random variable”
on page 271.
•Note that there is no built-in Excel function for computing the mean and variance of a
discrete random variable. But it can be done with Excel — see the Module Resources
for a video clip demonstrating how.
•The text has additional examples of how to apply the rules for means and variances that
are worth a look.
•The graphic illustrating different degrees of bias and variability in Figure 3.11 is quite
informative.
Sect. 4.4: The material in this section is very, very important – read it all twice. In particular:
•The concept of the sampling distribution of the sample mean gets used all over the place.
•The Central Limit Theorem tells us that the sampling distribution gravitates toward
normal regardless of the distribution of the underlying population. (Well, at least as
long as the variance is finite.) This is one of the most striking results in all of statistics.
•See the Module Resources for a video clip of an example involving the sampling distri-
bution of the sample mean.
Sect. 5.1: This section has numerous good examples illustrating probability rules. The entire
section is not that long and is worth reading.
•Be sure that you are clear on the distinction between independent and disjoint events.
Two events cannot be simultaneously independent and disjoint.
•The Multiplication Rule and General Addition Rule turn up in several of the homework
exercises.