Chapter 1
1. (Hypothetical) A researcher wants to determine the effectiveness of a high blood
pressure medicine.
She takes a random sample of 1,000 people and finds that 328 have
been diagnosed with high blood pressure.
She makes these 328 into the treatment group
and assigns the remainder to the control group.
She then administers the medicine to the
treatment group.
Is this an effective test of the medicine?
Why or why not?
2. (Hypothetical) In an effort to improve English grades, the principal of a high school
coordinates a special afterhours study session.
To populate the session, he randomly
chooses 15 students from each English class.
After one semester, he compares the
number of A’s for his special students with the number of A’s for everyone else.
The
results were as follows:
Total
A’s in English
Percent Rate
Special Group
60
17
28.3%
Regular Students
240
61
25.4%
a) Was this controlled study doubleblind?
Why or why not?
b) Does this data support a significant link between attending the sessions and higher
English grades?
Why or why not?
c) Give at least one possible confounding factor in this study.
3. Explain why, in general, researchers use placebos in the control group.
4. (AP) In 1998, a study was done to see if antiperspirant was effective at slowing the
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 Spring '08
 Patton
 Statistics, researcher, placebo, Scientific control, possible confounding factor

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