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Derive Ratio Variable

Source: R/derive_var_analysis_ratio.R
derive_var_analysis_ratio.Rd

Derives a ratio variable for a BDS dataset based on user specified variables.

Usage

derive_var_analysis_ratio(dataset, numer_var, denom_var, new_var = NULL)

Arguments

dataset

Input dataset

The variables specified by the numer_var and denom_var arguments are expected to be in the dataset.

numer_var

Variable containing numeric values to be used in the numerator of the ratio calculation.

denom_var

Variable containing numeric values to be used in the denominator of the ratio calculation.

new_var

A user-defined variable that will be appended to the dataset. The default behavior will take the denominator variable and prefix it with R2 and append to the dataset. Using this argument will override this default behavior.

Default is NULL.

Value

The input dataset with a ratio variable appended

Details

A user wishing to calculate a Ratio to Baseline, AVAL / BASE will have returned a new variable R2BASE that will be appended to the input dataset. Ratio to Analysis Range Lower Limit AVAL / ANRLO will return a new variable R2ANRLO, and Ratio to Analysis Range Upper Limit AVAL / ANRHI will return a new variable R2ANRLO. Please note how the denominator variable has the prefix R2----. A user can override the default returned variables by using the new_var argument. Also, values of 0 in the denominator will return NA in the derivation.

Reference CDISC ADaM Implementation Guide Version 1.1 Section 3.3.4 Analysis Parameter Variables for BDS Datasets

See also

BDS-Findings Functions that returns variable appended to dataset: derive_basetype_records(), derive_var_anrind(), derive_var_atoxgr(), derive_var_atoxgr_dir(), derive_var_base(), derive_var_chg(), derive_var_ontrtfl(), derive_var_pchg(), derive_var_shift(), derive_vars_crit_flag()

Examples

library(tibble)

data <- tribble(
  ~USUBJID, ~PARAMCD, ~SEQ, ~AVAL, ~BASE, ~ANRLO, ~ANRHI,
  "P01", "ALT", 1, 27, 27, 6, 34,
  "P01", "ALT", 2, 41, 27, 6, 34,
  "P01", "ALT", 3, 17, 27, 6, 34,
  "P02", "ALB", 1, 38, 38, 33, 49,
  "P02", "ALB", 2, 39, 38, 33, 49,
  "P02", "ALB", 3, 37, 38, 33, 49
)

# Returns "R2" prefixed variables
data %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = BASE) %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = ANRLO) %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = ANRHI)
#> # A tibble: 6 × 10
#>   USUBJID PARAMCD   SEQ  AVAL  BASE ANRLO ANRHI R2BASE R2ANRLO R2ANRHI
#>   <chr>   <chr>   <dbl> <dbl> <dbl> <dbl> <dbl>  <dbl>   <dbl>   <dbl>
#> 1 P01     ALT         1    27    27     6    34  1        4.5    0.794
#> 2 P01     ALT         2    41    27     6    34  1.52     6.83   1.21 
#> 3 P01     ALT         3    17    27     6    34  0.630    2.83   0.5  
#> 4 P02     ALB         1    38    38    33    49  1        1.15   0.776
#> 5 P02     ALB         2    39    38    33    49  1.03     1.18   0.796
#> 6 P02     ALB         3    37    38    33    49  0.974    1.12   0.755

# Returns user-defined variables
data %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = BASE, new_var = R01BASE) %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = ANRLO, new_var = R01ANRLO) %>%
  derive_var_analysis_ratio(numer_var = AVAL, denom_var = ANRHI, new_var = R01ANRHI)
#> # A tibble: 6 × 10
#>   USUBJID PARAMCD   SEQ  AVAL  BASE ANRLO ANRHI R01BASE R01ANRLO R01ANRHI
#>   <chr>   <chr>   <dbl> <dbl> <dbl> <dbl> <dbl>   <dbl>    <dbl>    <dbl>
#> 1 P01     ALT         1    27    27     6    34   1         4.5     0.794
#> 2 P01     ALT         2    41    27     6    34   1.52      6.83    1.21 
#> 3 P01     ALT         3    17    27     6    34   0.630     2.83    0.5  
#> 4 P02     ALB         1    38    38    33    49   1         1.15    0.776
#> 5 P02     ALB         2    39    38    33    49   1.03      1.18    0.796
#> 6 P02     ALB         3    37    38    33    49   0.974     1.12    0.755