LW1949 (version 1.0.0)

LWnomo1: Recreate Litchfield and Wilcoxon's Nomograph No. 1

Description

Recreate Litchfield and Wilcoxon's (1949) nomograph to estimate the contribution to the chi-squared from the expected percent effect and the observed minus the expected percent effect.

Usage

LWnomo1(values = FALSE)

Arguments

values

A logical scalar indicating whether values should be output.

Value

If values is TRUE, a list of length four, with the x and y coordinates and the corresponding values (all displayed in the log10 scale) of the end points of the three scales. Information is provided twice for the first scale, once for the left tick marks and once for the right tick marks.

Details

Use the nomograph by laying a straight edge from the expected percent effect in the first scale to the observed (corrected, if necessary) minus the expected percent effect in the second scale and reading the point where the straight edge crosses the third scale as the contribution.

The formula behind the nomograph is (observed - expected)^2 / (100 * expected)

References

Litchfield, JT Jr. and F Wilcoxon. 1949. A simplified method of evaluating dose-effect experiments. Journal of Pharmacology and Experimental Therapeutics 96(2):99-113. [link].

Examples

LWnomo1()