A researcher collects a set of 60 news articles about recent statements by Vladimir Putin
about Syria. The set includes 22 articles from The Sun, 18 from The New York Times, 11
from the Washington Post, 5 from the Boston Globe, and 4 from the Chicago Tribune.
a) If one article is selected at random, what is the probability it is not from the Globe or
Tribune?
b) If three articles are selected at random (without replacement), what is the probability
that at least one is from the Globe or Tribune?
Consider a training program designed to help immigrants incorporate into local communities.
Suppose event A is a participant leaving the program before it ends, with P(A) = 0:23,
event B is a participant having limited English prociency, with P(B) = 0:40, and event C
is obtaining a job in the rst week, with P(C) = 0:55. Suppose that events A and B are
independent and events B and C are mutually exclusive.
a) What is the probability that a participant leaves the program or has limited English
prociency?
b) What is the probability that a participant either has limited English prociency, or
obtains a job in the rst week?
In Congressional elections, donors contribute vast sums of money. These donors hope to
in uence the political decisions that Senators make in their favor. The best way to in uence
a Senator is to schedule meetings with him/her. Consider this (ctional) example: In the
last election cycle, of all donors to Senator Crawford, 5% were big donors, 25% were medium
donors, and 70% were small donors. 95% of the big donors, 30% of the medium donors, and
1% of the small donors were successful in scheduling meetings with Senator Crawford.
a) If one donor is selected at random and we learn that this donor did not get a meeting
scheduled with Senator Crawford, what is the probability of this donor being a medium
donor?
b) If one donor is selected at random and we learn that this donor did get a meeting
scheduled with Senator Crawford, what is the probability of this donor being a big
donor?
Using your nal project data, identify one variable of interest that is binary or (quasi-)
continuous. This variable should be important to your paper { perhaps one of your primary
outcomes.
a) Describe the variable substantively and its (expected) role in your paper.
b) Calculate the sample proportion, mean, or a dierence in means for that variable { ^p,
or x, or YT ? YC.
c) Calculate the standard error around that ^p, x, or YT ? YC.
d) Form a 95% condence interval around that ^p, x, or YT ? YC.
e) Substantively interpret your condence interval. (\If we had access to 100 other sam-
ples of . . . and formed similar intervals, we’d expect . . . )
