Dr. V – Study Guide – Ch 18, plus “About proportions”
Descriptive Statistics
1.
Given a N (3.1 ft, 1.2), what is the name (and units) for 1.2? How would you interpret it?
The
population’s standard deviation is 1.2
ft
(same units). That measure of variability is roughly the
average distance of the data (or scores) from the 3.1 mean.
2.
A median is preferred (over a mean) when data is . . . . .
3.
How do you determine whether an observation is an outlier?
. . . Using a box plot,
be able to
determine the “boundaries” with the 1.5xIRQ rule
⇒
outliers.
4.
What adjectives could apply to histograms? What adjectives could apply to time plots? Why are
they different?
Vocabulary Words
– Understand the basic
meaning of the following: bar charts, histograms,
population, sample, parameter, statistic, estimate, observational study, experiment, explanatory
variable, response (or outcome), confounding variable, probability, conditional probability,
complement, mutually exclusive (or disjoint), independent, random variable, inference, bias
(response, nonresponse, selection).
Snoring vs Life of the Party (See p 244):
P(likestoparty) = ?, P(snore
and
likestoparty) = ?, P
(snores
or
likestoparty) = ?, P(likestoparty

snores) = ?. Are “snoring” and “likestoparty”
independent? Are snoring and likestoparty disjoint?
Ch 8 – Random Variables
About discrete distributions
1.
Suppose x = # phone calls over lunch to a particular office (X = 0, 1, 2, 3, 4) so that
x
0
1
2
3
4
P(x)
0.2
0.35
0.25
0.12
?
a.
What’s the P(X=4)?
. . .
complement rule
gives you P(X=4)
b.
What’s the expected number of phone calls?
. . . When you see “expected” or E(X),
think MEAN (and means get decimals). Here, it’s E(X) =
Σ
xp(x) = 0x0.2 + 1x0.35 +
2x0.25 + etc.
c.