Example: Children’s
Television Viewing (from Activity 20-4)
Researchers
at Stanford studied whether reducing children’s television viewing might help
to prevent obesity. At the beginning of
the study, children were asked to report how many hours of television they
watch in a typical week. The 198 responses
had a mean of 15.41 hours and a standard deviation of 14.16 hours. Do these data provide evidence at the .05
level for concluding that third and fourth graders watch more than two hours of
television per day on average?
What Went Wrong? The
following are examples of potential errors one could make in this
analysis. In each case explain what the
problem is.
1.
The parameter is the amount of time that children spend watching television per
week.
2.
The hypotheses are H0 = 14 vs. Ha > 14
3.
The hypotheses are H0: 
= 14 vs. Ha: > 14
4.
The hypotheses are H0: 
= 15.41 vs. Ha:
< 15.41
5.
The test statistic is 
6.
The test statistic is 
7.
Because our p-value > .05, we can conclude that the children in the
population spend an average of two hours per day watching television.
8.
If the p-value had been very small, we would have concluded that all children
in the population watch more than two hours of television per day.
9.
If the p-value had been very small, we would have concluded that most children
in the population watch more than two hours of television per day.