(D) The first question probably shoed 25% and the second question 70% because of response bias due to the
wording of the questions.
(E) The first question probably showed 70% and the second question 25% because of response bias due to
the wording of the questions. As bolded in the question above, these ideas will provoke response bias
because people will answer in the way they think the interviewer wants them to answer or it will simply make
them think about that particular side of the issue.
4. Which of the following are true statements?
I. Voluntary response samples often underrepresent people with strong opinions. False - exactly the opposite!
Voluntary response bias refers to when ONLY the people with strong opinions respond to a survey. Because
otherwise why would you spend your precious time responding?
II. Convenience samples often lead to undercoverage bias. True – undercoverage refers to when parts of the
population are left out. So if you survey your family and friends, you are leaving out MANY people. If you call
people in the phone book you are leaving out people who don’t have a phone number.
III. Questionnaires with nonneutral wording are likely to have response bias. True – nonneutral wording is meant
to provoke someone to answer a question a certain way.
(A) I and II
(B) I and III
(C) II and III
(D) I, II, and III
(E) None of the above give the complete set of true responses.
5. Each of the 29 NBA teams has 12 players. A sample of 58 players is to be chosen as follows. Each team will be asked
to place 12 cards with its players’ names into a hat and randomly draw out two names. The two names from each
team will be combined to make up the sample. Which of the following sampling techniques is being used in this
situation?
(A) Simple Random Sample – No, a SRS refers ONLY to when the entire sampling frame (part of population you are
sampling from) is numbered off or has their names put in a hat and you randomly choose from ALL the possible
people. It’s a very large and costly process usually. The technical “definition” of a SRS is that every possible
sample of size n has the same probability of being chosen. In this case, it would not be possible for, say, all of
the Dallas Mavericks to be chosen.
(B) Stratified Sample – YES! All the NBA players have been divided in strata by teams. From each team they will
randomly choose 2.
(C) Cluster Sample – No. This refers to when the population is divided into heterogenous groups (clusters) and a
certain number of whole clusters are chosen randomly. Then everyone in the cluster is included in the
sample. This is different from Stratified because in each strata a certain number is picked out randomly.
(D) Multi-stage Sample – No. This refers to when more than one sampling procedure is used. For example, we could
divide up GHS by grade level, then randomly pick a grade. Then, randomly pick a subject area, let’s say English.
Then from all the English classes we could randomly pick 1 (or however many). Then we could randomly pick a
certain number of people from each class (stratifying) or the entire class (clustering).
(E) Systematic Sample – No. This refers to when the sampling frame is numbered off or listed in some kind of order,
then a random starting place is chosen, and finally every n
th
person is selected for the sample.
6. To survey the opinions of bleacher fans at Wrigley Field, a surveyor plans to select every one-hundredth fan entering
the bleachers one afternoon. Will this result in a simple random sample of Cub fans who sit in the bleachers?
(A) Yes, because each bleacher fan has the same chance of being selected. – No they don’t. What about the people
who arrive early (or late)?
(B) Yes, but only if there is a single entrance to the bleachers. – Nope. Doesn’t matter. It’s still not the definition of a
SRS because not every sample has the same probability of being chosen.
(C) Yes, because the 99 out of 100 bleacher fans who are not selected will form a control group. – Um, no. Control
groups are for experiments, not surveys.
(D) Yes, because this is an example of systematic sampling, which is a special case of simple random sampling. No,
because systematic sampling is NOT SRS. SRS is its own thing and very specific.
(E) No, because not every sample of the intended size has an equal chance of being selected. Correct because
this is the definition of a simple random sample.