R/add_crude_inc_rate.r

In injuryepi/injuryepi: Miscellaneous functions for Injury Epi

add_crude_inc_rate <- function(data, count, population, s = 100000, r = 1, alpha = 0.05 ){
  
  # confidence intervals with Wilson method 
  #simpler than the direct method 
  
  count <- enquo(count)
  population <- enquo(population)
  
  suppressWarnings(suppressMessages(require(dplyr)))
  suppressWarnings(suppressMessages(require(tibble)))
  
    a <- data %>% pull(!!count)
    N <- data %>% pull(!!population)
    p <- a/N
    z <- -qnorm(alpha/2)
    moe <- ((z/sqrt(N))*sqrt(p*(1-p) + z^2/(4*N)))/(1+z^2/N)
    center <- (p+z^2/(2*N))/(1+z^2/N)
    lower_limit <- center-moe
    upper_limit <- center+moe
    
   data %>%
      add_column(crude_rate = round(p*s, r) , 
                 lower_crude_rate = round(lower_limit*s, r), 
                 upper_crude_rate = round(upper_limit*s, r))
}