The whitefly, which causes defoliation of shrubs and trees and a reduction in salable crop yields, has emerged as a pest in Southern California. In a study to determine factors that affect the life cycle of the whitefly, an experiment was conducted in which whiteflies were placed on two different types of plants at three different temperatures. The observation of interest was the total number of eggs laid by caged females under one of the six possible treatment combinations. Each treatment combination was run using five cages.

Excel output for Exercise 11.65

a. What type of experimental design has been used?
b. Do the data provide sufficient evidence to indicate that the effect of temperature on the number of eggs laid is different depending on the type of plant? Use the printout to test the appropriate hypothesis.
c. Plot the treatment means for cotton as a function of temperature. Plot the treatment means for cucumber as a function of temperature. Comment on the similarity or difference in these two plots.
d. Find the mean number of eggs laid on cotton and cucumber based on 15 observations each. Calculate a 95% confidence interval for the difference in the underlying population means.

Transcribed Image Text:

Temperature 70°F 77F 82°F Plant 37 21 Cotton 36 43 31 50 53 Cucumber 25 37 48 34 54 32 40 42 36 16 59 53 62 31 71 69 49 51 59 46 41 38 43 ANOVA Source of Variation Plant Temperature 487.4667 2 243.733 1.981 0.160 3.403 Interaction Within Tota P-value F crit 1512.3 1 1512.3 12.293 0.0024.260 df MS 111.2 2 55.6 0.452 0.642 3.403 2952.4 24 123.017 5063.367 29