Question

Tea, Coffee, and Your Immune System

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 study¹ 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.² The results are shown in Table 1 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.

Tea	5	11	13	18	20	47
	48	52	55	56	58
Coffee	0	0	3	11	15	16
	21	21	38	52

Table 1 Immune system response in tea and coffee drinkers

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(a) Use StatKey or other technology to estimate the difference in mean production for tea drinkers minus coffee drinkers.

Round your answer to two decimal places.

x¯t-x¯c= Enter your answer in accordance to item (a) of the question statement

(b) Give the standard error for the difference.

Round your answer to one decimal place.

standard error = Enter your answer in accordance to item (b) of the question statement

(c) Give a 95% confidence interval.

Round your answers to two decimal places.

The 95% confidence interval is Enter your answer in accordance to item (c) of the question statement to Enter your answer in accordance to item (c) of the question statement .

Answer 1