extension to handle more than two treatment arms

.github/workflows/R-CMD-check.yaml

@@ -43,7 +43,7 @@ jobs:
 
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
-          extra-packages: any::rcmdcheck, margins=?ignore
+          extra-packages: any::rcmdcheck
           needs: check
 
       - uses: r-lib/actions/check-r-package@v2

.github/workflows/pkgdown.yaml

@@ -34,14 +34,9 @@ jobs:
 
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
-          extra-packages: any::pkgdown, local::., margins=?ignore
+          extra-packages: any::pkgdown, local::.
           needs: website
 
-      - name: Install archived dependencies (margins)
-        run: |
-          R -e 'install.packages("https://cran.r-project.org/src/contrib/Archive/prediction/prediction_0.3.17.tar.gz")'
-          R -e 'install.packages("https://cran.r-project.org/src/contrib/Archive/margins/margins_0.3.26.tar.gz")'
-
       - name: Build site
         run: pkgdown::build_site_github_pages(new_process = FALSE, install = FALSE)
         shell: Rscript {0}

.github/workflows/rhub.yaml

@@ -60,7 +60,7 @@ jobs:
         with:
           token: ${{ secrets.RHUB_TOKEN }}
           job-config: ${{ matrix.config.job-config }}
-          extra-packages: any::rcmdcheck, margins=?ignore
+          extra-packages: any::rcmdcheck
       - uses: r-hub/actions/run-check@v1
         with:
           token: ${{ secrets.RHUB_TOKEN }}
@@ -90,7 +90,7 @@ jobs:
         with:
           job-config: ${{ matrix.config.job-config }}
           token: ${{ secrets.RHUB_TOKEN }}
-          extra-packages: any::rcmdcheck, margins=?ignore
+          extra-packages: any::rcmdcheck
       - uses: r-hub/actions/run-check@v1
         with:
           job-config: ${{ matrix.config.job-config }}

.github/workflows/test-coverage.yaml

@@ -23,7 +23,7 @@ jobs:
 
       - uses: r-lib/actions/setup-r-dependencies@v2
         with:
-          extra-packages: any::covr, margins=?ignore
+          extra-packages: any::covr
           needs: coverage
 
       - name: Test coverage

DESCRIPTION

@@ -1,6 +1,6 @@
 Package: beeca
 Title: Binary Endpoint Estimation with Covariate Adjustment
-Version: 0.1.3.9000
+Version: 0.2.0
 Authors@R: 
   c(person(given = "Alex", 
            family = "Przybylski", 
@@ -33,15 +33,15 @@ Maintainer: Alex Przybylski <[email protected]>
 License: LGPL (>= 3)
 Encoding: UTF-8
 Roxygen: list(markdown = TRUE)
-RoxygenNote: 7.2.3
+RoxygenNote: 7.3.2
 Suggests: 
     knitr,
     rmarkdown,
     testthat (>= 3.0.0),
     tidyr,
     marginaleffects,
     margins,
-    RobinCar (== 0.3.0)
+    RobinCar (>= 0.3.0)
 Config/testthat/edition: 3
 Depends: 
     R (>= 2.10)

NAMESPACE

@@ -17,4 +17,5 @@ importFrom(stats,predict)
 importFrom(stats,terms)
 importFrom(stats,var)
 importFrom(stats,vcov)
+importFrom(utils,combn)
 importFrom(utils,packageVersion)

NEWS.md

@@ -1,4 +1,6 @@
-# beeca (development version)
+# beeca 0.2.0
+
+- Extensions to allow for more than two treatment arms in the model fit.
 
 # beeca 0.1.3
 

R/apply_contrast.R

@@ -27,9 +27,10 @@
 #' The choice of contrast affects how treatment effects are calculated and
 #' interpreted. Default is `diff`.
 #'
-#' @param reference a string indicating which treatment group should be considered as
-#' the reference level. Accepted values are one of the levels in the treatment
-#' variable. Default to the first level used in the `glm` object.
+#' @param reference a string or list of strings indicating which treatment
+#' group(s) to use as reference level for pairwise comparisons. Accepted values
+#' must be a subset of the levels in the treatment variable. Default to the
+#' first n-1 treatment levels used in the `glm` object.
 #'
 #' This parameter influences the calculation of treatment effects
 #' relative to the chosen reference group.
@@ -68,18 +69,19 @@
 #' fit3$marginal_est
 #' fit3$marginal_se
 #'
+#' @importFrom utils combn
 #' @export
 #'
 apply_contrast <- function(object, contrast = c("diff", "rr", "or", "logrr", "logor"), reference) {
-  # assert means are available in object
+  # Assert means are available in object
   if (!"counterfactual.means" %in% names(object)) {
     msg <- sprintf(
       "Missing counterfactual means. First run `%1$s <- average_predictions(%1$s)`.",
       deparse(quote(object))
     )
     stop(msg, call. = FALSE)
   }
-  # assert varcov is available in object
+  # Assert varcov is available in object
   if (!"robust_varcov" %in% names(object)) {
     msg <- sprintf(
       "Missing robust varcov. First run `%1$s <- get_varcov(%1$s, ...)`.",
@@ -92,53 +94,81 @@ apply_contrast <- function(object, contrast = c("diff", "rr", "or", "logrr", "lo
   object <- .assert_sanitized(object, trt, warn = T)
 
   data <- .get_data(object)
-  # assert non-missing reference
+
+  # Assert non-missing reference or set default
   if (missing(reference)) {
-    reference <- object$xlevels[[trt]][1]
-    warning(sprintf("No reference argument was provided, using %s as the reference level", reference), call. = FALSE)
+    reference <- object$xlevels[[trt]][-nlevels(data[[trt]])]
+    warning(sprintf("No reference argument was provided, using {%s} as the reference level(s)", paste(reference, collapse = ", ")), call. = FALSE)
+  }
+
+  # Assert reference to be subset of the treatment levels
+  if (!all(reference %in% levels(data[[trt]]))) {
+    stop("Reference levels must be a subset of treatment levels : ", paste(levels(data[[trt]]), collapse = ", "), ".")
   }
 
-  # assert reference to be one of the treatment levels
-  if (!reference %in% levels(data[[trt]])) {
-    stop("Reference must be one of : ", paste(levels(data[[trt]]), collapse = ", "), ".")
+  # Only accept at most nlevels(trt)-1 reference levels
+  if (length(reference) > (nlevels(data[[trt]])-1)) {
+    stop(sprintf("Too many reference levels provided. Expecting at most %s value(s) from the possible treatment levels: {%s}",
+                 nlevels(data[[trt]]) - 1,
+                 paste(levels(data[[trt]]), collapse = ", ")))
   }
 
-  # match contrast argument and retrieve relevant functions
+  # Match contrast argument and retrieve relevant helper functions
   contrast <- match.arg(contrast)
   c_est <- get(contrast)
   c_str <- get(paste0(contrast, "_str"))
   c_grad <- get(paste0("grad_", contrast))
 
-  # set reference to 1 if it is the first level
-  reference_n <- which(levels(data[[trt]]) == reference)
-  cf_mean_ref <- object$counterfactual.means[reference_n]
-  cf_mean_inv <- object$counterfactual.means[3 - reference_n]
-
-  trt_ref <- reference
-  trt_inv <- levels(data[[trt]])[-reference_n]
+  # Extract counterfactual means
+  cf_means <- object$counterfactual.means
 
-  # apply contrast to point estimate
-  marginal_est <- c_est(cf_mean_inv, cf_mean_ref)
+  # Get all pairwise arm comparisons for contrasts
+  # Format according to specified reference levels
+  l <- levels(data[[trt]])
+  combos <- combn(l, 2, \(x) {
+    if (any(reference %in% x)) {
+      ref <- intersect(reference, x)[[1]]
+      comp <- x[x!=ref]
+      c(which(ref == l), which(comp==l))
+    } else {
+      c(NA, NA)
+    }
+  })
+  combos <- combos[, is.finite(colSums(combos)), drop=F]
+  if (length(reference) > 1) {
+    combos <- combos[,order(combos[1,])]
+  }
+  idxs <- matrix(F, nrow=length(l), ncol=length(l))
+  rownames(idxs) <- colnames(idxs) <- l
+  idxs[cbind(combos[2,], combos[1,])] <- T
 
-  object$marginal_est <- marginal_est
-  names(object$marginal_est) <- "marginal_est"
-  attr(object$marginal_est, "reference") <- trt_ref
-  attr(object$marginal_est, "contrast") <- paste0(contrast, ": ", c_str(trt_inv, trt_ref))
 
-  # apply contrast to varcov
-  gr <- c_grad(cf_mean_inv, cf_mean_ref)
+  # Get marginal estimates for the contrasts of interest, using correct ref levels
+  marginal_est <- outer(cf_means, cf_means, c_est)
+  marginal_est <- marginal_est[idxs]
 
-  robust_varcov <- object$robust_varcov
+  # Define contrast jacobian
+  gr <- matrix(0, nrow=ncol(combos), ncol=length(l))
+  # Apply the grad function to all combinations
+  contrast_values <- t(apply(combos, 2, function(idx) c_grad(cf_means[idx[2]], cf_means[idx[1]])))
+  gr[cbind(1:ncol(combos), combos[1,])] <- contrast_values[, 1]
+  gr[cbind(1:ncol(combos), combos[2,])] <- contrast_values[, 2]
+  # Get marginal standard error for contrasts of interest
+  marginal_se <- sqrt(diag(gr %*% object$robust_varcov %*% t(gr)))
 
-  # correct varcov order based on reference
-  if (reference_n == 2) diag(robust_varcov) <- rev(diag(robust_varcov))
+  # Add string description for each comparison
+  contrast_desc <- paste0(contrast, ": ",
+                          apply(combos, 2, \(x) c_str(l[x[2]], l[x[1]])))
+  names(marginal_est) <- contrast_desc
+  names(marginal_se) <- contrast_desc
 
-  marginal_se <- sqrt(t(gr) %*% robust_varcov %*% gr)
+  object$marginal_est <- marginal_est
+  attr(object$marginal_est, "reference") <- reference
+  attr(object$marginal_est, "contrast") <- contrast_desc
 
-  object$marginal_se <- marginal_se[[1]]
-  names(object$marginal_se) <- "marginal_se"
-  attr(object$marginal_se, "reference") <- trt_ref
-  attr(object$marginal_se, "contrast") <- paste0(contrast, ": ", c_str(trt_inv, trt_ref))
+  object$marginal_se <- marginal_se
+  attr(object$marginal_se, "reference") <- reference
+  attr(object$marginal_se, "contrast") <- contrast_desc
   attr(object$marginal_se, "type") <- attr(object$robust_varcov, "type")
 
   return(object)