When exposed to an infection, a person typically develops antibodies. The extent to which the antibodies respond can be measured by looking at a person's titer, which is a measure of the number of antibodies present. The higher the titer is, the more antibodies that are present. The data in Table 9 represent the titers of 11 ill people and 11 healthy people exposed to the tularemia virus in Vermont. Is the level of titer in the ill group greater than the level of titer in the healthy group? Use the \(\alpha=0.1\) level of significance.

Approach Normal probability plots indicate that the sample data do not come from a population that is normal. Therefore, we will use the Mann-Whitney test. We then proceed to follow Steps 1 through 5.

Transcribed Image Text:

Table 9 III Healthy 640 160 1280 320 10 320 160 160 80 640 640 160 320 320 10 320 1280 640 160 320 80 640