The article "Cooperative Hunting in Lions: The Role of the Individual" (Behavioral Ecology and Sociobiology [1992]: 445-454) discusses the different roles taken by lionesses as they attack and capture prey. The authors were interested in the effect of the position in line as stalking occurs. An individual lioness may be in the center of the line or on the wing (end of the line) as they advance toward their prey. In addition to position, the role of the lioness was also considered. A lioness could initiate a chase (be the first one to charge the prey), or she could participate and join the chase after it has been initiated. Data from the article are summarized in the accompanying table.
a. Is there evidence of an association between position and role?
b. What assumptions about how the data were collected must be true for the chi-square test to be an appropriate way to analyze these data?