Answer:
Co-relation between the independent variables i.e a) Diet type and
b) Time of the day would lead to misleading conclusions
Explanation:
Courtney was actually trying to test the effect of her diet on her racing times. But instead of making an observation with respect to diet type, she also started making observations for "time of the day" vs. "racing time"
Earlier there was only one independent variable i.e "diet type" whose impact on dependent variable "racing time" was to be studied. But by the end of the test there were two independent variables-
a) Diet type and
b) Time of the day.
Since, Courtney has no understanding of co-relation between the above two independent variable. It was very difficult for Courtney to come to a exact solution.