STAT 101  Agresti
Homework 2 Solutions
9/17/10
Chapter 3
3.33. The mean, standard deviation, maximum, and range all increase, because the observation for D.C.
was a high outlier. Note that these statistics are not resistant to outliers. On the other hand, the median,
Q3, Q1, the interquartile range, and the mode remain the same, as these are all resistant to outliers. The
minimum remains the same since D.C. was a high outlier and not a low outlier.
3.39. (a) Minimum = 0, Q1 = 2, median = 3, Q3 = 5, maximum = 14. (b) Same as part (a). (c) The
observations with values 12 and 14 are outliers. (d) The standard deviation is 3.
3.41. (a)
10.0
15.0
20.0
25.0
No health insurance
(b) The distribution appears to be skewed to the right, because of the long distance between the upper
quartile and the maximum.
3.43. (a) Minimum = 1, Q1 = 3, median = 5, Q3 = 6, maximum = 13. (b)
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5.0
7.5
10.0
12.5
MU_noDC
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Louisiana appears to be a mild outlier. (c) Minimum = 1, Q1 = 3, median = 5, Q3 = 6, maximum = 44.
0
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MU
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Louisiana is still a mild outlier, and D.C. is an extreme outlier. Only the maximum changes in the five
number summary when the observation for D.C. is added to the data set.
3.47. (a) Response variable: opinion about national health insurance (favor, oppose); explanatory
variable: political party (Democrat, Republican). (b) The data could be summarized in a contingency table
with political party as the rows and opinion about national health insurance as the columns.
3.48. (a) Response variable: happiness; explanatory variable: religious attendance. (b) For those who
attend religious services nearly every week or more, 44.5% reported being very happy. For those who
attend religious services never or less than once a year, 23.2% reported being very happy. (c) There
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 Fall '10
 ALAN
 Statistics, Standard Deviation, standard deviations

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