30.11 Quick review questions

A study (Y.-M. Lee et al. 2016) compared using a vegan (\(n=46\)) and a conventional (\(n=47\)) diet for 12 weeks, for a group of Koreans with Type II diabetes. A summary of the data for iron levels are shown in Table 30.4.

TABLE 30.4: Comparing the iron levels (mg) for subjects using a vegan or conventional diet for 12 weeks

	Mean	Std. dev	n
Vegan diet	13.9	2.3	46
Conventional diet	15	2.7	47
Difference	1.1

1. The sample size is missing from the ‘Difference’ row. What should the sample size in this row be?
   46 + 47 = 93 46 - 47 = -1 47 - 46 = 1 A sample size makes no sense There is not enough information
2. What is the standard deviation for the difference?
   0.3391 0.3928 A standard deviation makes no sense There is not enough information
3. What is the standard error for the difference?
   0.3391 0.3928 A standard error makes no sense There is not enough information
4. The two-tailed \(P\)-value for the comparison is given as \(P=0.046\). What does this mean?
   There is no evidence that the sample means are different There is some evidence that the sample means are different There is no evidence that the population means are different There is some evidence that the population means are different There is not enough information