r2_mckelvey function

McKelvey & Zavoinas R2

Calculates McKelvey and Zavoinas pseudo R2.

r2_mckelvey(model)

Arguments

• model: Generalized linear model.

Returns

The R2 value.

Details

McKelvey and Zavoinas R2 is based on the explained variance, where the variance of the predicted response is divided by the sum of the variance of the predicted response and residual variance. For binomial models, the residual variance is either pi^2/3

for logit-link and 1 for probit-link. For poisson-models, the residual variance is based on log-normal approximation, similar to the distribution-specific variance as described in ?insight::get_variance.

Examples

## Dobson (1990) Page 93: Randomized Controlled Trial:
counts <- c(18, 17, 15, 20, 10, 20, 25, 13, 12) #
outcome <- gl(3, 1, 9)
treatment <- gl(3, 3)
model <- glm(counts ~ outcome + treatment, family = poisson())

r2_mckelvey(model)

References

McKelvey, R., Zavoina, W. (1975), "A Statistical Model for the Analysis of Ordinal Level Dependent Variables", Journal of Mathematical Sociology 4, S. 103–120.