Question: Grackles, commonly referred to as blackbirds, are hosts for a parasitic worm that lives in the tissue around the brain. To see if the incidence of this parasite was changing, 24 blackbirds were captured and the number of brain parasites in each bird was recorded. These data were compared with the infestation of 16 birds captured from the same place 10 years earlier. Analyze the data with a Mann-Whitney test and write a conclusion. Be careful and systematic in assigning ranks. Errors here are quite frustrating.
