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Calculates McKelvey and Zavoinas pseudo R2.

Usage

r2_mckelvey(model)

Arguments

model

Generalized linear model.

Value

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.

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.

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)
#> McKelvey's R2 
#>     0.3776292