Using the data in Practice Problem 11, state whether each of the following sets of numbers (items a through f) is a possible permuted sample for use in testing the difference between the means of singleton and twin birth weights. If not, explain why.

Data from practice problem 11

For each of the sets of samples in the accompanying figures (a)–(e), state which approach is best if the goal is to test the difference between the means of group 1 (on the left) and group 2 (on the right). Pay careful attention to differences between samples in the scales of the x-axis.These graphs have not been drawn according to the best practices that we outlined in Chapter 2 (histograms of two samples should be displayed one above the other and on the same scale), but they are similar to those you might obtain if you plotted them separately with a computer program.

(a)

(b) 

(c) 

(d)

(e)