An occupational health study was carried out to evaluate the health status of workers. The response is forced expiratory volume (FEV), a measure of respiratory function. Observations are made on n=12 individuals in each of three plants where workers are exposed primarily to one of three toxic substances, depending on the section of the plant where they work. Suppose that the toxic substances are the only ones of interest and the plants were randomly selected from a large population of similar plants.
The data resulted in the following ANOVA table:
Source SS df MS
Substance 66.89 2 33.445
Plant 13.30 2 6.65
Interaction 24.50 4 6.125
Error 26.58 99 . 2685
Total 131.27 107
Answer the next 3 questions based on these data.
 In this experiment, the number of treatments is
 Using the above data, one can estimate variance components for
a) error and plant
b) error and substance
c) error, plant, and interaction
d) error, substance, and interaction
e) error, substance, plant, and interaction
 The estimated component of variance due to plants is
This posting contains answers to following 3 questions based on the output of ANOVA given below.