The shape of a distribution is a rough guide to whether the mean and standard deviation are
Question:
The shape of a distribution is a rough guide to whether the mean and standard deviation are a helpful summary of center and spread. For which of these distributions would x and sbe useful? In each case, give a reason for your decision.
(a) Percent of high school graduates in the states taking the SAT as shown below
a. The distribution is fairly symmetric, and therefore x and s are useful measures.
b. x and s are resistant measures, and therefore are not useful measures for asymmetric distributions.
c. x and s are useful descriptions of the center and spread for any type of distribution.
d. The distribution is not symmetric, and therefore x and s are not useful measures.
(b) Iowa Test scores as shown below
a. x and s are useful descriptions of the center and spread for any type of distribution.
b. x is useful but s isn't because the distribution is symmetric.
c. The distribution is fairly symmetric and free of outliers, and therefore x and s are useful measures.
d. x and s are resistant measures, and therefore they don't work for symmetric distribution.
(c) New York travel times as shown below
a. x and s are useful descriptions of the center and spread for any type of distribution.
b. s is useful but x isn't because of the tail on the left.
c. x and s are resistant measures, and therefore they aren't influenced by the skewed distribution.
d. The tail on the right strongly influences both x and s, so they are not very useful.