diff --git a/data-raw/simulate-data.R b/data-raw/simulate-data.R
index 00d83fb..5235416 100644
--- a/data-raw/simulate-data.R
+++ b/data-raw/simulate-data.R
@@ -29,12 +29,33 @@ library(rvest)
 
 # Simulation functions -----------------------------------------------------
 
+#'  Zero pad an integer to a specific length
+#'
+#' @param x An integer or vector of integers.
+#' @param width An integer describing the final width of the zero-padded integer.
+#' @keywords internal
+#'
+#' @return A character vector of integers.
+#'
+#' @examples
+#' pad_integers(x = 1, width = 5)
+#' pad_integers(x = c(1, 2, 3), width = 10)
 pad_integers <- function(x, width) {
   x |>
     stringr::str_trunc(width = width, side = "left", ellipsis = "") |>
     stringr::str_pad(width = width, side = "left", pad = "0")
 }
 
+#' Create a vector with random ICD-8 or -10 diagnoses
+#'
+#' @param n The number of ICD-8 or -10 diagnoses to generate.
+#' @param date A date determining whether the diagnoses should be ICD-8 or ICD-10. If null, a random date will be sampled to determine which ICD revision the diagnosis should be from. In the Danish registers, ICD-10 is used after 1994.
+#'
+#' @return A character vector of ICD-10 diagnoses.
+#'
+#' @examples
+#' create_fake_icd(10)
+#' create_fake_icd(5, "1995-04-19")
 create_fake_icd <- function(n, date = NULL) {
   if (is.null(date)) {
     date <- sample(c("1993-01-01", "1995-01-01"), 1)
@@ -47,6 +68,17 @@ create_fake_icd <- function(n, date = NULL) {
   }
 }
 
+#' Create a vector of random ICD-8 diagnoses
+
+#' @description
+#' ICD-8 is the 8th revision of the International Classification of Diseases.
+#' 
+#' @param n The number of ICD-8 diagnoses to generate.
+#'
+#' @return A character vector of ICD-8 diagnoses.
+#'
+#' @examples
+#' create_fake_icd8(1)
 create_fake_icd8 <- function(n) {
   here("data-raw/icd8-codes.csv") |>
     read_csv() |>
@@ -54,6 +86,17 @@ create_fake_icd8 <- function(n) {
     sample(size = n, replace = TRUE)
 }
 
+#' Create a vector of random ICD-10 diagnoses.
+#'
+#' @description
+#' ICD-10 is the 10th revision of the International Classification of Diseases.
+#' 
+#' @param n An integer determining how many diagnoses to create.
+#'
+#' @return A character vector of ICD-10 diagnoses.
+#'
+#' @examples
+#' create_fake_icd10(3)
 create_fake_icd10 <- function(n) {
   # from: https://medinfo.dk/sks/brows.php?s_nod=6308
   here("data-raw/icd10-codes.csv") |>
@@ -62,6 +105,18 @@ create_fake_icd10 <- function(n) {
     sample(size = n, replace = TRUE)
 }
 
+#' Create a vector with random ATC codes
+#'
+#' @description
+#' Anatomical Therapeutic Chemical (ATC) codes are unique medicine codes
+#' based on on what organ or system it works on and how it works.
+#' 
+#' @param n The number of random ATC codes to generate.
+#'
+#' @return A character vector of ATC codes.
+#'
+#' @examples
+#' create_fake_atc(10)
 create_fake_atc <- function(n) {
   codeCollection::ATCKoodit |>
     tibble::as_tibble() |>
@@ -70,17 +125,49 @@ create_fake_atc <- function(n) {
     sample(n, replace = TRUE)
 }
 
+#' Create fake dates
+#'
+#' @param n The number of dates to generate.
+#' @param from A date determining the first date in the interval to sample from.
+#' @param to A date determining the last date in the interval to sample from.
+#'
+#' @return A vector of dates.
+#'
+#' @examples
+#' create_fake_date(20)
+#' create_fake_date(20, "1995-04-19", "2024-04-19")
 create_fake_date <- function(n, from = "1977-01-01", to = lubridate::today()) {
   seq(as_date(from), as_date(to), by = "day") |>
     sample(n, replace = TRUE)
 }
 
+#' Create a vector of random zero-padded integers.
+#'
+#' @param n The number of integers to generate.
+#' @param length An integer determining the length of the padded integer.
+#'
+#' @return A character vector of integers.
+#'
+#' @examples
+#' create_padded_integer(5, 10)
 create_padded_integer <- function(n, length) {
   purrr::map(1:length, \(ignore) sample(0:9, n, replace = TRUE)) |>
     purrr::reduce(\(integer1, integer2) paste(integer1, integer2, sep = "")) |>
     pad_integers(width = length)
 }
 
+#' Create a vector of random NPU codes
+#'
+#' @description
+#' Nomenclature for Properties and Units (NPUs) are codes that identifies
+#' laboratory results.
+#' 
+#' @param n The number of NPUs to create.
+#'
+#' @return A character vector.
+#'
+#' @examples
+#' create_fake_npu(4)
 create_fake_npu <- function(n) {
   stringr::str_c(
     "NPU",
@@ -88,6 +175,14 @@ create_fake_npu <- function(n) {
   )
 }
 
+#' Create a vector of random department specialties
+#'
+#' @param n The number of department specialties to create.
+#'
+#' @return A character vector.
+#'
+#' @examples
+#' create_fake_hovedspeciale_ans(1000)
 create_fake_hovedspeciale_ans <- function(n) {
   "https://www.dst.dk/da/Statistik/dokumentation/Times/forebyggelsesregistret/spec" |>
     read_html() |>
@@ -97,6 +192,15 @@ create_fake_hovedspeciale_ans <- function(n) {
     sample(n, replace = TRUE)
 }
 
+#' Create a vector of drug names based on a vector of ATC codes
+#'
+#' @param atc A character describing an ATC code.
+#'
+#' @return A character vector with the drug name of the given ATC code.
+#'
+#' @examples
+#' create_fake_drug_name("A03FA05")
+#' create_fake_drug_name(c("A03FA05", "A02BA04"))
 create_fake_drug_name <- function(atc) {
   codeCollection::ATCKoodit |>
     tibble::as_tibble() |>
@@ -105,20 +209,56 @@ create_fake_drug_name <- function(atc) {
     sample(length(atc), replace = TRUE)
 }
 
+#' Transform date(s) to the format wwyy
+#'
+#' @param x A date or a vector of dates.
+#'
+#' @return A vector of dates in the format wwyy.
+#'
+#' @examples
+#' to_wwyy("2020-12-01")
+#' to_wwyy(c("2020-01-12", "1995-04-19"))
 to_wwyy <- function(x) {
   paste0(lubridate::isoweek(lubridate::as_date(x)), stringr::str_sub(lubridate::isoyear(lubridate::as_date(x)), -2))
 }
 
+#' Transform date(s) to the format yyyymmdd
+#'
+#' @param x A date or a vector of dates.
+#'
+#' @return A vector of dates in the format yyyymmdd.
+#'
+#' @examples
+#' to_yyyymmdd("2020-12-01")
+#' to_yyyymmdd(c("2020-01-12", "1995-04-19"))
 to_yyyymmdd <- function(x) {
   format(lubridate::as_date(x), format = "%Y%m%d")
 }
 
 # Insert extra values to overrepresent certain values ------------------------------------------------------
 
+#' Generate logic based on a probability
+#'
+#' @param proportion A double between 0 and 1.
+#'
+#' @return A logic vector. TRUE if the random number is less than the proportion,
+#' otherwise FALSE.
+#'
+#' @examples
+#' insertion_rate(0.3)
 insertion_rate <- function(proportion) {
   runif(1) < proportion
 }
 
+#' Insert specific ATC codes based on a proportion
+#'
+#' @param data A tibble.
+#' @param proportion Proportion to be resampled. Defaults to 0.3.
+#'
+#' @return A tibble with a proportion of resampled ATC codes for columns
+#' named 'atc'
+#'
+#' @examples
 insert_specific_atc <- function(data, proportion = 0.3) {
   glucose_lowering_drugs <- c(
     metformin = "A10AB02",
@@ -149,42 +289,67 @@ insert_specific_atc <- function(data, proportion = 0.3) {
     )
 }
 
-# Insert a few cases where purchases of metformin are used for other purposes
-# than diabetes.
+#' Insert cases where metformin is used for other purposes than diabetes
+#'
+#' @description
+#' This function uses the variable 'indo' which is the code for the underlying
+#' condition treated by the prescribed medication.
+#'
+#' @param data A tibble.
+#' @param proportion Proportion to resample. Defaults to 0.05.
+#'
+#' @return A tibble. If all column names in the tibble is either 'atc' or
+#' 'name', a proportion of observations is resampled as metmorfin.
 insert_false_metformin <- function(data, proportion = 0.05) {
-  if (!all(colnames(data) %in% c("atc", "name"))) {
-    return(data)
-  }
-  data |>
-    dplyr::mutate(
-      atc = dplyr::if_else(
-        indo %in% c("0000092", "0000276", "0000781") & insertion_rate(proportion),
-        "A10BA02",
-        atc
-      ),
-      name = dplyr::if_else(
-        indo %in% c("0000092", "0000276", "0000781") & insertion_rate(proportion),
-        "metformin",
-        name
+  if (all(c("atc", "name", "indo") %in% colnames(data))) {
+    data |>
+      dplyr::mutate(
+        atc = dplyr::if_else(
+          indo %in% c("0000092", "0000276", "0000781") & insertion_rate(proportion),
+          "A10BA02",
+          atc
+        ),
+        name = dplyr::if_else(
+          indo %in% c("0000092", "0000276", "0000781") & insertion_rate(proportion),
+          "metformin",
+          name
+        )
       )
-    )
+  } else {
+  data
+  }
 }
 
-# Insert some false positives for Wegovy and Saxenda.
+# Insert false positives for Wegovy and Saxenda
+#'
+#' @param data A tibble.
+#' @param proportion Proportion to resample. Defaults to 0.05.
+#'
+#' @return A tibble. If all column names in the tibble is either 'atc' or 'name'
+#' and the atc is a A10BJ06 or A10BJ02, a proportion of observations is resampled
+#' to have the name Wegovy Flextouch or Saxenda.
 insert_false_drug_names <- function(data, proportion = 0.05) {
-  if (!all(colnames(data) %in% c("atc", "name"))) {
-    return(data)
-  }
-  data |>
-    mutate(
-      name = case_when(
-        atc == "A10BJ06" & insertion_rate(proportion) ~ "Wegovy Flextouch",
-        atc == "A10BJ02" & insertion_rate(proportion) ~ "Saxenda",
-        TRUE ~ name
+  if (all(c("atc", "name") %in% colnames(data))) {
+    data |>
+      mutate(
+        name = case_when(
+          atc == "A10BJ06" & insertion_rate(proportion) ~ "Wegovy Flextouch",
+          atc == "A10BJ02" & insertion_rate(proportion) ~ "Saxenda",
+          TRUE ~ name
+        )
       )
-    )
+  } else {
+    data
+  }
 }
 
+#' Insert additional analysis codes for HbA1c
+#'
+#' @param data A tibble.
+#' @param proportion Proportion to resample. Defaults to 0.3.
+#'
+#' @return A tibble. If a column is named "analysiscode", a proportion of the
+#' values are replaced by codes for HbA1c.
 insert_analysiscode <- function(data, proportion = 0.3) {
   # NPU27300: New units for HbA1c
   # NPU03835: Old units for HbA1c
@@ -201,11 +366,32 @@ insert_analysiscode <- function(data, proportion = 0.3) {
     )
 }
 
+#' Add drug names (from ATC codes)
+#'
+#' @param data A tibble.
+#'
+#' @return A tibble. For columns named "name", a fake drug name (atc) will be
+#' added.
+add_fake_drug_name <- function(data) {
+  data |>
+    mutate(
+      across(
+        matches("^name$"),
+        \(x) create_fake_drug_name(atc = atc)
+      )
+    )
+}
+
 # TODO: Need a function to reuse recnum and dw_ek_kontakt in LPR data
 
 # Simulate data -----------------------------------------------------------
 
-# use the simulation definition data to simulate some data
+#' Simulate data based on simulation definitions
+#'
+#' @param data A tibble with simulation definitions.
+#' @param n Number of observations to simulate.
+#'
+#' @return A tibble with simulated data.
 simulate_data <- function(data, n) {
   # N needs to be capitalized for fabricatr, and but to be consistent
   # with other functions and their use of `n`, I kept it lowercase for
@@ -222,16 +408,6 @@ simulate_data <- function(data, n) {
     list_cbind()
 }
 
-add_fake_drug_name <- function(data) {
-  data |>
-    mutate(
-      across(
-        matches("^name$"),
-        \(x) create_fake_drug_name(atc = atc)
-      )
-    )
-}
-
 set.seed(123)
 simulation_definitions <- here("data-raw/simulation-definitions.csv") |>
   read_csv(show_col_types = FALSE) |>