This function creates a multi-way table of counts
for the response given a set of classifying factors. Output
facilitates a check on how the factor specified as margin
may, after accounting for other classifying factors, affect the
response.
excessRisk(form = weight ~ seatbelt + airbag, response = "dead", margin = "airbag",
data = DAAG::nassCDS, decpl = 4, printResults = TRUE)form is a formula in which classifying factors
appear on the right, with an optional weight variable on the left.
response is a binary variable or two-level
factor such that the response of interest is the relative number
in the two levels.
margin is the factor whose effect on the
response,
after accounting for other classifying factors, is of interest
data is a data frame in which variables and
factors may be found
decpl is the number of decimal places in
proportions that appear in the output
if TRUE, a tabular summary is printed.
The function returns a data frame, with one row for each combination of
levels of factors on the right of the formula, but excluding the
factor specified as margin
Count for level 2 of response \& level 1 of margin
Total tount for level 1 of margin
Count for level 2 of response \& level 2 of margin
Total count for level 2 of margin
Proportion; divide count for level 1 of margin by total
Proportion; divide count for level 2 of margin by total
Excess count for level 2 of response in row; relative to
the assumption that, in that row, there is no association between
response and margin. This is the observed response
(for the default arguments, number of dead) for level 2 (airbag deployed),
less the number that would have been expected if the proportion
had been that for level 1. (Negative values favor airbags.)
The best way to understand what this function does may be to run it with the default parameters, and/or with examples that appear below.
See help(nassCDS)
xtabs
# NOT RUN {
excessRisk()
excessRisk(weight ~ airbag+seatbelt+dvcat)
UCB <- as.data.frame.table(UCBAdmissions)
excessRisk(Freq~Gender, response="Admit", margin="Gender",data=UCB)
excessRisk(Freq~Gender+Dept, response="Admit", margin="Gender",data=UCB)
# }
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