An experiment studied the effects of starch source, starch concentration, and temperature on the strength of gels. This experiment was completely randomized with sixteen units. There are four starch sources (adzuki bean, corn, wheat, and potato), two starch percentages (5% and 7%), and two temperatures (22oC and 4oC). The response is gel strength in grams (data from Tjahjadi 1983).
Analyze these data to determine the effects of the factors on gel strength.