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Bland-Altman statistics

Source: R/ba_stat.R
ba_stat.Rd

The function is computing all relevant Bland-Altman statistics, including bias, lower and upper limits of agreement and their confidence limits.

Usage

ba_stat(
  data = stop("data must be specified"),
  var1 = stop("variable must be specified"),
  var2 = stop("variable must be specified"),
  group = NULL,
  alpha = 0.05,
  transform = c("identity", "log", "logit")
)

Arguments

data

A data frame

var1

1st variable to compare (unquoted)

var2

2nd variable to compare (unquoted)

group

grouping variable (unquoted)

alpha

alpha level for the intervals

transform

Transformation to apply before computing statistics. One of "identity" (default), "log", or "logit". Delegates to ba_mean_diff.

Value

A tibble with three variables n (number of observations), parameter and value is returned.

See also

ba_plot

Examples

library(tidyr)
tbl <- temperature |> pivot_wider(names_from = method, values_from = temperature)

# simple example
ba_stat(data = tbl, var1 = infrared, var2 = rectal)
#> # A tibble: 9 × 3
#>       n parameter   value
#>   <int> <chr>       <dbl>
#> 1   450 bias       0.234 
#> 2   450 lloa      -2.85  
#> 3   450 uloa       3.32  
#> 4   450 bias.lcl   0.0879
#> 5   450 lloa.lcl  -3.10  
#> 6   450 uloa.lcl   3.07  
#> 7   450 bias.ucl   0.379 
#> 8   450 lloa.ucl  -2.60  
#> 9   450 uloa.ucl   3.57  

## example with grouping
ba_stat(data = tbl, var1 = infrared, var2 = rectal, group = treatment) |>
  pivot_wider(names_from = parameter, values_from = value)
#> # A tibble: 6 × 11
#>   treatment     n   bias  lloa  uloa bias.lcl lloa.lcl uloa.lcl bias.ucl
#>   <fct>     <int>  <dbl> <dbl> <dbl>    <dbl>    <dbl>    <dbl>    <dbl>
#> 1 healthy      75 0.202  -2.51  2.92  -0.116     -3.06     2.37    0.521
#> 2 vehicle      75 0.0383 -3.23  3.30  -0.345     -3.88     2.65    0.422
#> 3 low dose     75 0.0353 -3.16  3.23  -0.339     -3.80     2.58    0.410
#> 4 mid dose     75 0.634  -2.45  3.72   0.273     -3.07     3.09    0.996
#> 5 high dose    75 0.173  -3.15  3.50  -0.218     -3.82     2.83    0.563
#> 6 SoC          75 0.319  -2.50  3.14  -0.0125    -3.07     2.57    0.650
#> # ℹ 2 more variables: lloa.ucl <dbl>, uloa.ucl <dbl>