Statistics in a Modern World 800
Solutions to Exam 1
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- (i) sample survey/observational study (researchers only tested;
they imposed no changes)
- (iii) type of surface
- (ii) bacteria level
- (i) funding (see last sentence); an easy way to increase Clorox sales
would be to convince people that they need to clean their desks more
- (i) unknown; there were apparently many of each of the twelve
types of surfaces tested
-
- (ii) experiment; researchers did impose a treatment, namely the
program to help children earn good grades and get along with others
- (ii)schoolchildren in high-crime areas (schoolchildren is too
general; 350 schoolchildren in high-crime areas comprise the sample,
not the population)
-
(ii) response variable
-
(i) explanatory variable
-
(i) categorical variable
-
(ii) discrete measurement variable
-
yes, since specific choices were provided
-
- University of Washington Social Development Research Group
- 350 students (and their parents and teachers) in 18 Seattle schools
in high-crime areas between 1981 and 1986
- A. participants in a program to earn good grades and get along
with others; B. non-participants
- 38; 56
-
(iii) about the same---15% or 16%---for both groups
-
(ii) prospective
-
(ii) no; students would know if they were involved in the program
- (iii) unreliable measure
- (iii) desire to please
-
- (i) confounding variables
- (i) outgoing, high-achieving girls tend to participate in sports,
and they also tend to succeed as adults
- (iii) make the assignments at random; (ii) large sample is better
- (iii)experiment
- (b) children who attended preschool may tend to come from families with
a higher income, and thus less likely to commit crimes
- (ii) apparently no, since the percentages of"yes" and "no" answers
add up to 100%
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