Calculate Positive Likelihood Ratio

Calculates the Positive Likelihood Ratio (LR+) from a confusion matrix object. LR+ compares the probability of a positive test result among patients with the disease to the probability of a positive test result among patients without the disease.

Usage

dx_lrt_pos(cm, detail = "full", ...)

Arguments

cm

A dx_cm object created by dx_cm().

detail

Character specifying the level of detail in the output: "simple" for raw estimate, "full" for detailed estimate including 95% confidence intervals.

...

Additional arguments to pass to metric_binomial function, such as citype for type of confidence interval method.

Value

Depending on the detail parameter, returns a numeric value representing the calculated metric or a data frame/tibble with detailed diagnostics including confidence intervals and possibly other metrics relevant to understanding the metric.

Details

The positive likelihood ratio is calculated as (TP / (TP + FN)) / (FP / (FP + TN)). It is used to assess the diagnostic usefulness of a test. A LR+ much greater than 1 indicates a good diagnostic test that can confidently confirm the disease when the test is positive.

Examples

cm <- dx_cm(dx_heart_failure$predicted, dx_heart_failure$truth,
  threshold =
    0.5, poslabel = 1
)
simple_lrp <- dx_lrt_pos(cm, detail = "simple")
detailed_lrp <- dx_lrt_pos(cm)
print(simple_lrp)
#> [1] 8.700157
print(detailed_lrp)
#> # A tibble: 1 × 8
#>   measure summary           estimate conf_low conf_high fraction conf_type notes
#>   <chr>   <chr>                <dbl>    <dbl>     <dbl> <chr>    <chr>     <chr>
#> 1 LRT+    8.70 (5.08, 14.9…     8.70     5.08      14.9 ""       Large sa… ""