Add SMD Column to Demographics/Baseline Table

Adds a standardized mean difference column to a baseline characteristics table, flagging variables that exceed the imbalance threshold. This is essential for GBA/AMNOG dossiers to demonstrate baseline comparability.

Usage

add_smd_to_table(
  data,
  trt_var,
  vars,
  ref_group = NULL,
  threshold = 0.1,
  conf_level = 0.95,
  continuous_threshold = 10,
  flag_symbol = "*"
)

Arguments

data

A data frame containing the baseline data.

trt_var

Character. Name of the treatment variable.

vars

Character vector. Names of variables to calculate SMD for.

ref_group

Character or NULL. Reference (control) group value. If NULL, uses the first level.

threshold

Numeric. SMD threshold for flagging imbalance (default: 0.1). Common thresholds are 0.1 (strict) and 0.25 (lenient).

conf_level

Numeric. Confidence level for CI (default: 0.95)

continuous_threshold

Integer. Minimum number of unique values to treat numeric variables as continuous (default: 10).

flag_symbol

Character. Symbol to use for flagging imbalanced variables (default: "*")

Value

A data frame with columns:

• variable: Variable name

• smd: Standardized mean difference

• ci: Formatted confidence interval

• imbalanced: Logical flag for |SMD| > threshold

• smd_display: Formatted SMD with flag if imbalanced

References

IQWiG (2020). General Methods: Version 6.0. Institute for Quality and Efficiency in Health Care.

See also

assess_baseline_balance(), create_love_plot()

Examples

if (FALSE) { # \dontrun{
adsl <- data.frame(
  AGE = rnorm(200, 55, 12),
  WEIGHT = rnorm(200, 75, 15),
  SEX = sample(c("M", "F"), 200, replace = TRUE),
  TRT01P = rep(c("Treatment", "Placebo"), each = 100)
)

smd_table <- add_smd_to_table(
  data = adsl,
  trt_var = "TRT01P",
  vars = c("AGE", "WEIGHT", "SEX"),
  ref_group = "Placebo"
)
} # }