Answer:
Step-by-step explanation:
To test the research question of whether birds preferentially prey upon moths with respect to their resting backgrounds, we could alter Kettlewell's experimental design in the following ways:
Increase the sample size: One issue with Kettlewell's original study was the small sample size. To increase the power of the study, we could increase the number of moths and birds tested. This could involve setting up multiple experimental arenas, each with a different background, and testing multiple birds and moths within each arena.
Randomize the backgrounds: In Kettlewell's original study, the experimental arenas were set up with specific backgrounds (e.g., light and dark tree trunks). To avoid potential confounding variables, we could randomize the backgrounds for each arena. For example, we could use a computer program to generate random backgrounds for each arena, ensuring that there is an equal distribution of light and dark backgrounds.
Blind the observers: Another potential issue with Kettlewell's study is observer bias, where the experimenters may unconsciously favor data that supports their hypothesis. To avoid this, we could blind the observers to the background and moth type. For example, we could set up the experiment in such a way that the observers cannot see the background or the type of moth being tested.
Control for other variables: We could also control for other variables that may impact bird predation, such as temperature, humidity, and wind speed. By controlling for these variables, we can ensure that any differences in moth predation are due to the resting background and not other extraneous factors.
Overall, by altering Kettlewell's experimental design in these ways, we can conduct a more robust study that addresses potential confounding variables and has higher statistical power.