Inferant Statistics

ANOVA of the Fruitfly Data

In this activity, you will be performing an ANOVA on the fruitfly data to determine whether the longevity of males is related to their reproductive cycle. Studies have shown that the longevity of female fruitflies decreases with an increase in reproduction.

The design of the study placed male fruitflies in the following groups: males living alone, males living with one interested female, males living with eight interested females, males living with one uninterested female, and males living with eight uninterested females. The hypothesis was that the males living alone and with the uninterested females would live longer than the males living with the interested females. Since there are more than two group means, an ANOVA is used to determine if there is a significant difference between the group means.

Using either Excel or the TI-83 graphing calculator, perform an ANOVA to determine if there is a significant difference between the groups. If there is a significant difference, you will need to determine the means that are significantly different by doing a Tukey Test.

This data exists in three files; one is in Excel Data format, one is in Text format, and one is in TI-83 Group format. If you want to perform the ANOVA using the TI-83, you will have to import the text data into the calculator from the computer after you have downloaded the file.

Is there a significant difference between the groups? If so, between which ones? If you used Excel, what were the F and F-critical values? the p value? If you used the TI-83, what was the p value? What does the p value tell you in terms of the significance of the results? Does reproductive activity affect the longevity of male fruitflies?

Oh, if you are wondering how one determines "interest" in fruitflies, here is the scoop! Newly inseminated females will not usually mate again for at least two days. So the males in the uninterested groups were always living with newly inseminated females!