Summarize the ratio of two variables

This helper, to be used with tbl_custom_summary(), creates a function computing the ratio of two continuous variables and its confidence interval.

ratio_summary(numerator, denominator, na.rm = TRUE, conf.level = 0.95)

Arguments

numerator

String indicating the name of the variable to be summed for computing the numerator.

denominator

String indicating the name of the variable to be summed for computing the denominator.

na.rm

Should missing values be removed before summing the numerator and the denominator? (default is TRUE)

conf.level

Confidence level for the returned confidence interval. Must be strictly greater than 0 and less than 1. Default to 0.95, which corresponds to a 95 percent confidence interval.

Details

Computed statistics:

• {num} sum of the variable defined by numerator

• {denom} sum of the variable defined by denominator

• {ratio} ratio of num by denom

• {conf.low} lower confidence interval

• {conf.high} upper confidence interval

Confidence interval is computed with stats::poisson.test(), if and only if num is an integer.

Example Output

Example 1

See also

Other tbl_custom_summary tools: add_overall(), continuous_summary(), proportion_summary(), tbl_custom_summary()

Author

Joseph Larmarange

Examples

# Example 1 ----------------------------------
ratio_summary_ex1 <-
  trial %>%
  tbl_custom_summary(
    include = c("stage", "grade"),
    by = "trt",
    stat_fns = ~ ratio_summary("response", "ttdeath"),
    statistic = ~"{ratio} [{conf.low}; {conf.high}] ({num}/{denom})",
    digits = ~ c(3, 2, 2, 0, 0),
    overall_row = TRUE,
    overall_row_label = "All stages & grades"
  ) %>%
  bold_labels() %>%
  modify_footnote(
    update = all_stat_cols() ~ "Ratio [95% CI] (n/N)"
  )