Carotenoids are pigments responsible for much of the red we see in nature. For example, the bright
Question:
Carotenoids are pigments responsible for much of the red we see in nature. For example, the bright red beak color of the male zebra finch is derived from carotenoids. Carotenoids are also important as antioxidants for humans and other animals, leading researchers to predict that carotenoids in birds may affect immune system function. To test this, a group of zebra finches was randomly divided into two groups (McGraw and Ardia 2003).
Ten individual finches received supplemental carotenoids in their diet, and 10 individuals did not. All 20 birds were then measured using an assay that measures cell-mediated immunocompetence (PHA) as well as an assay that measures humoral immunity (SRBC). The data are given below. The researchers had independent reasons to believe that neither assay score would be normally distributed, so they preferred a nonparametric test.
a. Does PHA differ on average between the birds that received supplemental carotenoids and those that did not?
b. Does SRBC differ on average between the birds that received supplemental carotenoids and those that did not?
c. What assumptions did you require in parts (a) and (b)?
Step by Step Answer:
a To determine if PHA differs on average between the birds that received supplemental carotenoids and those that did not well perform a nonparametric ...View the full answer
The Analysis Of Biological Data
ISBN: 9781319226237
3rd Edition
Authors: Michael C. Whitlock, Dolph Schluter
