Environmental Data Analysis EESC
BC 3017
Homework 7 - due Th 11/20
Regression analysis
1.) (8p)
Open the BCancer.xls workbook from the Berk&Carey CD. Create a
scatter plot of mortality vs. temperature and add a linear trend line
to the plot showing both R2 and the regression equation. Calculate the
regression statistics. Is there a significant linear correlation
between mortality due to breast cance and temperature?
Significance tests
3.)
(8p) Ttest on cell experiments. Chemical
compounds that are
carcinogenic to mammals also commonly cause genetic mutations in lower
organisms. Preliminary screening of possible cancer-producing compounds
can be performed by testing whether these compounds increase the
mutation
rate of microorganisms. Comparison of the log transformed colony counts
of the untreated and treated groups can provide evidence for the safety
of the chemical. (The logarithm of the colony count is used here
instead
of the count itself, because the data are heavily skewed. So, "2"
stands
for 102 colonies = 100 colonies).
Perform a ttest on the log colony counts as given in the table below
to find out if there is sufficient evidence for the hypothesis that the
particular chemical tested affects cell numbers/mutations.
| Control |
Treatment
|
|
2.13
|
1.42
|
|
1.59
|
1.73
|
|
1.14
|
1.57
|
|
1.77
|
1.49
|
|
1.36
|
2.52
|
|
1.46
|
1.83
|
|
1.19
|
1.35
|
| |
1.53
|