Occupation and diet, continued. Use of the pooled two-sample t test is justified in part (b) of the previous exercise. Explain why. Find the P-value for the pooled t statistic, and compare it with your result in the previous exercise.
Exercise
Occupation and diet. Do the diets of various occupational groups differ? A British study of this question compared 98 drivers and 83 conductors of London double-decker buses.40 The conductors' jobs require more physical activity. The article reporting the study gives the data as "Mean daily consumption (± se)." Some of the study results follow:
(a) What does "se" stand for? Give x‾ and s for each of the four sets of measurements.
(b) Is there significant evidence at the 5% level that conductors consume more calories per day than do drivers? Use the two-sample t method to give a P-value, and then assess significance.
(c) How significant is the observed difference in mean alcohol consumption? Use two-sample t methods to obtain the P-value.
(d) Give a 95% confidence interval for the mean daily alcohol consumption of London double-decker bus conductors.
(e) Give a 99% confidence interval for the difference in mean daily alcohol consumption between drivers and conductors.