Ant counts on samples of different sandwiches
A data frame with 48 observations on the following 5 variables.
Butter Butter on the sandwich?
Filling Type of filling:
Ham \& Pickles,
Bread Type of bread:
Ants Number of ants on the sandwich
Order Trial number
As young students, Dominic Kelly and his friends enjoyed watching ants
gather on pieces of sandwiches. Later, as a university student, Dominic
decided to study this with a more formal experiment. He chose three types of
sandwich fillings (vegemite, peanut butter, and ham \& pickles), four types
of bread (multigrain, rye, white, and wholemeal), and put butter on some of
To conduct the experiment he randomly chose a sandwich, broke off a piece, and left it on the ground near an ant hill. After several minutes he placed a jar over the sandwich bit and counteed the number of ants. He repeated the process, allowing time for ants to return to the hill after each trial, until he had two samples for each combination of the three factors.
Margaret Mackisack, “Favourite Experiments: An Addendum to What is the Use of Experiments Conducted by Statistics Students?", Journal of Statistics Education (1994) http://www.amstat.org/publications/jse/v2n1/mackisack.supp.html