Per-study responder risk differences

Dichotomizes each study at the MID threshold and returns the per-study responder risk difference (experimental minus control) with a confidence interval. Building block for the "individual" method of responder_analysis(); also feeds the forest plot and per-study table.

Usage

responder_rd_individual(
  data,
  mid,
  direction = c("higher", "lower"),
  se_method = c("binomial", "delta"),
  conf_level = 0.95,
  dist = c("normal", "lognormal", "t"),
  df = NULL,
  mid_sd = 0
)

Arguments

data

A data frame with one row per study and columns study, change_e, sd_e, n_e, change_c, sd_c, n_c. See sample_responder_data.

mid

Single finite number: the minimal important difference threshold.

direction

"higher" (a larger change indicates response) or "lower".

se_method

Per-study SE model for "individual": "binomial" (default) or "delta". The "binomial" variance p(1 - p) / n is a pseudo-binomial approximation: p is a probability implied by the estimated mean and SD, not a proportion of observed dichotomized patients, so it does not include the uncertainty in the reported mean and SD. "delta" propagates that uncertainty and is generally preferable for summary-statistic inputs; "binomial" is the default only for continuity with earlier results.

conf_level

Confidence level (default 0.95).

dist

Change-score distribution: "normal" (default), "lognormal" or "t".

df

Degrees of freedom when dist = "t".

mid_sd

Optional standard deviation of the MID threshold; when > 0 its uncertainty is propagated into the effect-measure variances.

Value

A data frame with one row per study and columns study, p_e, p_c, rd, se, ci_lb, ci_ub (proportion scale).

See also

responder_analysis()

Examples

responder_rd_individual(sample_responder_data, mid = 1)
#>     study       p_e       p_c        rd         se      ci_lb     ci_ub
#> 1 Study 1 0.4867232 0.2564577 0.2302655 0.10023645 0.03380566 0.4267253
#> 2 Study 2 0.4355507 0.2259278 0.2096229 0.05454152 0.10272350 0.3165223
#> 3 Study 3 0.5068639 0.2047187 0.3021452 0.05106129 0.20206690 0.4022235