Fungicide: Carcinogenic Effects of a Fungicide

In vcdExtra: 'vcd' Extensions and Additions

Carcinogenic Effects of a Fungicide

Description

Data from Gart (1971) on the carcinogenic effects of a certain fungicide in two strains of mice. Of interest is how the association between group (Control, Treated) and outcome (Tumor, No Tumor) varies with sex and strain of the mice.

Format

The data comprise a set of four 2 x 2 tables classifying 403 mice, either Control or Treated and whether or not a tumor was later observed. The four groups represent the combinations of sex and strain of mice.

The format is:

num [1:2, 1:2, 1:2, 1:2] 5 4 74 12 3 2 84 14 10 4 ...
- attr(*, "dimnames")=List of 4
..$ group  : chr [1:2] "Control" "Treated"
..$ outcome: chr [1:2] "Tumor" "NoTumor"
..$ sex    : chr [1:2] "M" "F"
..$ strain : chr [1:2] "1" "2"

Details

Breslow (1976) used this data to illustrate the application of linear models to log odds ratios.

All tables have some small cells, so a continuity correction is recommended.

Source

Gart, J. J. (1971). The comparison of proportions: a review of significance tests, confidence intervals and adjustments for stratification. International Statistical Review, 39, 148-169.

References

Breslow, N. (1976), Regression analysis of the log odds ratio: A method for retrospective studies, Biometrics, 32(3), 409-416.

Examples

data(Fungicide)
# loddsratio was moved to vcd; requires vcd_1.3-3+
## Not run: 
fung.lor <- loddsratio(Fungicide, correct=TRUE)
fung.lor
confint(fung.lor)

## End(Not run)

# visualize odds ratios in fourfold plots
cotabplot(Fungicide, panel=cotab_fourfold)
#  -- fourfold() requires vcd >= 1.2-10
fourfold(Fungicide, p_adjust_method="none")

vcdExtra documentation built on Dec. 11, 2025, 9:06 a.m.