Advertisers fear that users of DVRs (digital video recorders) will “fast forward” past commercials when they watch a recorded program. A leading British pay television company told its advertisers that this effect might be offset because DVR users watch more TV. A sample of 15 DVR users showed a daily mean screen time of 2 hours and 26 minutes with a standard deviation of 14 minutes, compared with a daily mean of 2 hours and 7 minutes with a standard deviation of 12 minutes for a sample of 15 non-DVR users. (a) Construct a 95 percent confidence interval for the difference in mean TV watching. Would this sample support the company’s claim (i.e., is zero within the confidence interval for the mean difference)? (b) Discuss any assumptions that are needed.
Advertisers fear that users of DVRs (digital video recorders) will “fast forward” past commercials when they watch a recorded program. A leading British pay television company told its advertisers that this effect might be offset because DVR users watch more TV. A sample of 15 DVR users showed a daily mean screen time of 2 hours and 26 minutes with a standard deviation of 14 minutes, compared with a daily mean of 2 hours and 7 minutes with a standard deviation of 12 minutes for a sample of 15 non-DVR users. (a) Construct a 95 percent confidence interval for the difference in mean TV watching. Would this sample support the company’s claim (i.e., is zero within the confidence interval for the mean difference)? (b) Discuss any assumptions that are needed.
Solution Summary: The author states that the sample does not support the company's claim.
Advertisers fear that users of DVRs (digital video recorders) will “fast forward” past commercials when they watch a recorded program. A leading British pay television company told its advertisers that this effect might be offset because DVR users watch more TV. A sample of 15 DVR users showed a daily mean screen time of 2 hours and 26 minutes with a standard deviation of 14 minutes, compared with a daily mean of 2 hours and 7 minutes with a standard deviation of 12 minutes for a sample of 15 non-DVR users. (a) Construct a 95 percent confidence interval for the difference in mean TV watching. Would this sample support the company’s claim (i.e., is zero within the confidence interval for the mean difference)? (b) Discuss any assumptions that are needed.
Definition Definition Number of subjects or observations included in a study. A large sample size typically provides more reliable results and better representation of the population. As sample size and width of confidence interval are inversely related, if the sample size is increased, the width of the confidence interval decreases.
a small pond contains eight catfish and six bluegill. If seven fish are caught at random, what is the probability that exactly five catfish have been caught?
23 The line graph in the following figure shows
Revenue ($ millions)
one company's revenues over time. Explain
why this graph is misleading and what you
can do to fix the problem.
700
60-
50-
40
30
Line Graph of Revenue
20-
101
1950
1970
1975 1980 1985
Year
1990
2000
d of the
20
respectively.
Interpret the shape, center and spread of the
following box plot.
14
13
12
11
10
6
T
89
7
9
5.
治
Chapter 10 Solutions
Gen Combo Ll Applied Statistics In Business & Economics; Connect Access Card
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