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Statistics 601, Fall 2006
Assignment 3
On the course web page under “Laboratory Materials” is a link to data sets called
“lrtrt.txt” and “lrcon.txt”. These files contain four columns each. The first two
columns contain values appropriate to form an X-matrix for generalized linear models of cadmium concentration on length – column 1 is all 1s for an intercept term
and column two contains values of length for individual fish. Column 3 contains the
response variable of cadmium concentration and the fourth column is junk (again
all 1s). Get these data into R using “read.table”. The file “lrtrt.txt” is for the
treatment basin and the file “lrcon.txt” is for the control basin.
Your assignment is to write a short report on the analysis of these data using
standard generalized linear models. Somewhere in your report include all of the
following:
1. A description of the various models (random component and systematic component combinations) that you tried to fit to the two data sets.
2. Evidence that forms the basis of your choice of model for each of the data sets.
3. Parameter estimates for your choice of final model for each data set.
4. Evidence that forms the basis for a conclusion about whether the relation
between length and cadmium concentration differs between the control and
treatment basins and, if so, in what ways.
5. For at least one of the basins, a 95% point-wise confidence band for the regression function.