Veterinary study of downer cows (cattle unable to rise after calving). The outcome is whether the animal survived to discharge.
Format
A data frame with 216 rows and 5 variables:
- AST
Aspartate aminotransferase (enzyme marker): 0 = normal, 1 = elevated.
- CK
Creatine kinase (enzyme marker): 0 = normal, 1 = elevated.
- Calving
Whether the downer condition was related to calving: 0 = No, 1 = Yes.
- Myopathy
Presence of myopathy: factor with levels
"No","Yes".- Survival
Outcome: factor with levels
"Died","Survived". Binary outcome.
Source
Dohoo, I., Martin, W. & Stryhn, H. (2003). Veterinary Epidemiologic Research. AVC Inc., Prince Edward Island, Canada.
Examples
data(downer)
prop.table(table(downer$Survival))
#>
#> Died Survived
#> 0.7453704 0.2546296
fit <- glm(as.integer(Survival == "Survived") ~ Myopathy + AST + CK + Calving,
family = binomial, data = downer)
prLogisticDelta(fit)
#>
#> Prevalence Ratio Estimation via Logistic Regression
#> ----------------------------------------------------
#> Model : glm
#> Method : delta
#> Standardis. : conditional
#> Conf. level : 95%
#> ----------------------------------------------------
#>
#> Estimate 2.5% 97.5%
#> MyopathyYes 0.3034 0.1001 0.9191
#> AST 1.1900 0.5273 2.6857
#> CK 2.0026 0.8604 4.6611
#> Calving 0.7809 0.4080 1.4946
#>