In Exercise 3.82, we introduce a study to estimate the difference in mean immune response (as measured in the study) between tea drinkers and coffee drinkers. The data are given in Table 3.12 on page 204 and are available in Immune Tea.

Table 3.12

(a) Give a point estimate for the difference in means: tea drinkers mean immune response minus coffee drinkers mean immune response.
(b) What quantity are we estimating? Give the correct notation.
(c) Using StatKey or other technology, construct and interpret a 90% confidence interval.
(d) Using StatKey or other technology, construct and interpret a 99% confidence interval.
(e) Based on this sample and the results in parts (c) and (d), are we 90% confident that tea drinkers have a stronger immune response? Are we 99% confident?

Exercise 3.82

Researchers suspect that drinking tea might enhance the production of interferon gamma, a molecule that helps the immune system fight bacteria, viruses, and tumors. A recent study involved 21 healthy people who did not normally drink tea or coffee. Eleven of the participants were randomly assigned to drink five or six cups of tea a day, while 10 were asked to drink the same amount of coffee. After two weeks, blood samples were exposed to an antigen and production of interferon gamma was measured. The results are shown in Table 3.12 and are available in ImmuneTea. We are interested in estimating the effect size, the increase in average interferon gamma production for drinking tea when compared to coffee. Use StatKey or other technology to estimate the difference in mean production for tea drinkers minus coffee drinkers. Give the standard error for the difference and a 95% confidence interval. Interpret the result in context.

Transcribed Image Text:

Tea 5 48 11 13 18 20 47 52 55 56 58 3 38 11 Coffee 15 16 21 21 52 3.