Problems 477
and samples are obtained from flowers stored under three conditions: fresh flowers,
flowers stored for 1 year, and flowers stored for 1 year but treated. It is assumed
that there is no interaction present. The data are as follows:
Pyrethrin Content, Percent
Method
Storage
Condition A B C D
1 1.35 1.13 1.06 .98
2 1.40 1.23 1.26 1.22
3 1.49 1.46 1.40 1.35Suggest a model for the preceding information, and use the data to estimate its
parameters.
20.The following data refer to the number of deaths per 10,000 adults in a large
Eastern city in the different seasons for the years 1982 to 1986.Year Winter Spring Summer Fall
1982 33.6 31.4 29.8 32.1
1983 32.5 30.1 28.5 29.9
1984 35.3 33.2 29.5 28.7
1985 34.4 28.6 33.9 30.1
1986 37.3 34.1 28.5 29.4(a) Assuming a two-factor model, estimate the parameters.
(b) Test the hypothesis that death rates do not depend on the season. Use the
5 percent level of significance.
(c) Test, at the 5 percent level of significance, the hypothesis that there is no
effect due to the year.
21.For the model of Problem 19:
(a) Do the methods of extraction appear to differ?
(b) Do the storage conditions affect the content? Test at theα=.05 level of
significance.
22.Three different washing machines were employed to test four different detergents.
The following data give a coded score of the effectiveness of each washing.(a) Estimate the improvement in mean value when using detergent 1 over using
detergents (i) 2; (ii) 3; (iii) 4.
(b) Estimate the improvement in mean value when using machine 3 as opposed
to using machine (i) 1; (ii) 2.