excessRisk {DAAG}

Create and analyze multiway frequency or weighted frequency table

Description

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.

Usage

excessRisk(form = weight ~ seatbelt + airbag, response = "dead", margin = "airbag",
data = DAAG::nassCDS, decpl = 4, printResults = TRUE)

Arguments

form

form is a formula in which classifying factors appear on the right, with an optional weight variable on the left.

response

response is a binary variable or two-level factor such that the response of interest is the relative number in the two levels.

margin

margin is the factor whose effect on the response, after accounting for other classifying factors, is of interest

data

data is a data frame in which variables and factors may be found

decpl

decpl is the number of decimal places in proportions that appear in the output

printResults

if TRUE, a tabular summary is printed.

Details

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.

Value

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. The final three columns show the count for level 1 as a fraction of the margin by total, the count for level 2 as a fraction of the margin by total, and the excess count for level 2 of response in the row, under 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.)

Author(s)

John Maindonald

References

See help(nassCDS)

See Also

xtabs

Examples

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)