Thousands of motorists travel on Highway 27 everyday. Before installation of traffic cameras at mile marker 11, motorists' speeds averaged 72 mph. After installation of cameras, speeds averaged 67 mph. An independent samples t-test comparing the average speeds yielded a t-statistic of 10.32. Remember the critical value at p=.05 is 1.96. Assuming our data meet the requirements for conducting a t-test, what can we conclude from this result? a. There is less than a 5% chance that we would have observed this average difference if there really wasn't a difference in average speeds before and after the camera was installed. b. We cannot draw any conclusions because we should have used a one-sample t-test. c. We cannot draw any conclusions because the p-value is not reported. d. We cannot draw any conclusions because the standard deviation is not reported. e. We do not have enough informaton to draw any conclusions.
Thousands of motorists travel on Highway 27 everyday. Before installation of traffic cameras at mile marker 11, motorists' speeds averaged 72 mph. After installation of cameras, speeds averaged 67 mph. An independent samples t-test comparing the average speeds yielded a t-statistic of 10.32. Remember the critical value at p=.05 is 1.96. Assuming our data meet the requirements for conducting a t-test, what can we conclude from this result?
a. There is less than a 5% chance that we would have observed this average difference if there really wasn't a difference in average speeds before and after the camera was installed.
b. We cannot draw any conclusions because we should have used a one-sample t-test.
c. We cannot draw any conclusions because the p-value is not reported.
d. We cannot draw any conclusions because the standard deviation is not reported.
e. We do not have enough informaton to draw any conclusions.
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