Ezzet and Whitehead (1991) analyze data from a two-treatment, two-period crossover trial to compare 2 inhalation devices for delivering the drug salbutamol in 286 asthma patients. Patients were asked to rate the clarity of leaflet instructions accompanying each device, using a 4-point ordinal scale.
A data frame of 572 observations containing information on the following 5 variables.
The subject number
The rating of the inhaler instructions on a scale ranging from 1 to 4
A contrast to indicate which of the two inhaler devices was used
A contrast to indicate the time of administration
A contrast to indicate possible carry over effects
Ezzet, F., & Whitehead, J. (1991). A random effects model for ordinal responses from a crossover trial. Statistics in Medicine, 10(6), 901-907.
## Not run: ## ordinal regression with family "sratio" fit1 <- brm(rating ~ treat + period + carry, data = inhaler, family = sratio(), prior = set_prior("normal(0,5)")) summary(fit1) plot(fit1) ## ordinal regression with family "cumulative" ## and random intercept over subjects fit2 <- brm(rating ~ treat + period + carry + (1|subject), data = inhaler, family = cumulative(), prior = set_prior("normal(0,5)")) summary(fit2) plot(fit2) ## End(Not run)
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