ONLINE SUPPLEMENT - Beyond sex differences in mean: meta-analysis of differences in skewness, kurtosis, and correlation

Author

Pietro Pollo, Szymon M. Drobniak, Hamed Haselimashhadi, Malgorzata Lagisz, Ayumi Mizuno, Daniel W. A. Noble, Laura A. B. Wilson, Shinichi Nakagawa

1 Update

Last update March 2025.

We will update this tutorial when necessary. Readers can access the latest version in our GitHub repository.

If you have any questions, errors or bug reports, please contact Pietro Pollo (pietro_pollo@hotmail.com) or Shinichi Nakagawa (snakagaw@ualberta.ca).

2 Introduction

This online material is a supplement to our paper “Beyond sex differences in mean: meta-analysis of differences in skewness, kurtosis, and correlation”. You will see how to calculate the new effect size statistics we have proposed and how to use them in a meta-analytical model using the metafor package in R.

3 Content

In this online material, we will show how to (1) calculate our newly proposed effect sizes (\(\Delta sk\), \(\Delta ku\), \(\Delta Zr\)) and (2) exemplify their use with data from the International Mouse Phenotyping Consortium.

4 Prerequisites

4.1 Loading packages

Our tutorial uses R statistical software and existing R packages, which you will first need to download and install.

If the packages are archived in CRAN, use install.packages() to install them. For example, to install the metafor , you can execute install.packages("metafor") in the console (bottom left pane of R Studio).

Version information of each package is listed at the end of this tutorial.

Code
if (!require("pacman")) {install.packages("pacman")}
pacman::p_load(corrr,
               DT,
               ggdist,
               ggtext,
               here,
               janitor,
               metafor,
               pander,
               patchwork,
               tidyverse)

options(DT.options = list(rownames = FALSE,
                          dom = "Blfrtip",
                          scrollX = TRUE,
                          pageLength = 5,
                          columnDefs = list(list(targets = '_all', 
                                                 className = 'dt-center')),
                          buttons = c('copy', 'csv', 'excel', 'pdf')))

source("layout.R")

4.2 Custom functions

We also provide some additional helper functions to calculate effect sizes, process data, and visualise our results. The most straightforward way to use these custom functions is to run the code chunk below. Alternatively, paste the code into the console and hit Enter to have R ‘learn’ these custom functions.

If you want to use these custom functions in your own data, you will need to change the variable names according to your own data (check out the R code and you will see what we mean).

Code
# calculate effect sizes ----
## skewness ----
calc.skewness <- function(x, output = "est") {
  n <- length(x)
  
  if (output == "est") { # skewness estimate
    (sqrt(n * (n - 1)) / (n - 2)) *
      (((1 / n) * sum((x - mean(x)) ^ 3)) /
         (((1 / n) * sum((x - mean(x)) ^ 2)) ^ (3/2)))
    
  } else if (output == "var") { # skewness sampling variance
    (6 * n * (n - 1)) /
      ((n - 2) * (n + 1) * (n + 3))
  }
}

## kurtosis ----
calc.kurtosis <- function(x, output = "est") {
  n <- length(x)
  
  if (output == "est") { # kurtosis estimate
    ((((n + 1) * n * (n - 1)) / ((n - 2) * (n - 3))) *
       (sum((x - mean(x)) ^ 4) / (sum((x - mean(x)) ^ 2) ^ 2))) -
      (3 * ((n - 1) ^ 2) / ((n - 2) * (n - 3)))
  } else if (output == "var") { # kurtosis sampling variance
    (24 * n * ((n - 1) ^ 2)) /
      ((n - 3) * (n - 2) * (n + 3) * (n + 5))
  }
}

## Zr ----
r.to.zr <- # Zr estimate
  function(r) { 
    0.5 * log((1 + r) / (1 - r))
  }

zr.variance <- # Zr variance 
  function(n) {
    1 / (n - 3)
  }

## other effect sizes (lnRR and lnVR) ----
calc.effect <- function(data = raw_data, 
                        m) { # calculates other already established effect size statistics 
  escalc(measure = m,
         m1i = data$mean_male,
         m2i = data$mean_female,
         sd1i = data$sd_male,
         sd2i = data$sd_female,
         n1i = data$n_male,
         n2i = data$n_female,
         var.names = c(paste0(m,
                              "_est"),
                       paste0(m,
                              "_var")))
}

# processing functions ----
process.ind_effects <- function(chosen_trait = "fat_mass",
                                measure = "KU_delta") {
  ind_effects <-
    df_meta_analysed %>% 
    filter(trait_name == chosen_trait,
           phenotyping_center %in% c("CCP-IMG",
                                     "HMGU",
                                     "JAX",
                                     "MRC H",
                                     "TCP")) %>% 
    mutate(type = "individual") %>% 
    select(phenotyping_center,
           strain_fig,
           n = n_total,
           est = paste0(measure, "_", "est"),
           var = paste0(measure, "_", "var"),
           lower = paste0(measure, "_", "lower"),
           upper = paste0(measure, "_", "upper"))
  
  model <- rma.mv(data = ind_effects,
                  yi = est,
                  V = var,
                  test = "t",
                  random = list(~ 1|phenotyping_center, 
                                ~ 1|strain_fig))
  
  df_model <- data.frame(trait_name = chosen_trait,
                         est = model$beta[1],
                         var = model$se ^ 2,
                         lower = model$ci.lb,
                         upper = model$ci.ub,
                         phenotyping_center = "Mean",
                         strain_fig = "ES")
  
  
  ind_effects %>% 
    bind_rows(df_model) %>% 
    mutate(est_type = measure,
           centre_and_strain = factor(paste0(phenotyping_center,
                                             "\n",
                                             strain_fig))) %>% 
    mutate(centre_and_strain = factor(centre_and_strain,
                                      levels = c("Mean\nES",
                                                 rev(levels(centre_and_strain)[-6]))))
}

process.cor_effects <- function(chosen_trait_1 = "fat_mass",
                                chosen_trait_2 = "heart_weight") {
  df_effects_cor <-
    df_raw %>% 
    filter(trait_name %in% c(chosen_trait_1,
                             chosen_trait_2), 
           phenotyping_center %in% c("CCP-IMG",
                                     "HMGU",
                                     "JAX",
                                     "MRC H",
                                     "TCP")) %>% 
    pivot_wider(id_cols = c(specimen_id,
                            strain_fig,
                            phenotyping_center,
                            sex),
                names_from = trait_name) %>%
    clean_names() %>% 
    drop_na() %>% 
    group_by(strain_fig,
             phenotyping_center,
             sex) %>% 
    group_modify(~ correlate(.x)) %>% 
    drop_na(all_of(chosen_trait_2)) %>% 
    ungroup() %>%
    left_join(df_raw %>% 
                filter(trait_name %in% c(chosen_trait_1,
                                         chosen_trait_2), 
                       phenotyping_center %in% c("CCP-IMG",
                                                 "HMGU",
                                                 "JAX",
                                                 "MRC H",
                                                 "TCP")) %>% 
                pivot_wider(id_cols = c(specimen_id,
                                        strain_fig,
                                        phenotyping_center,
                                        sex),
                            names_from = trait_name) %>%
                clean_names() %>% 
                drop_na() %>% 
                group_by(strain_fig,
                         phenotyping_center,
                         sex) %>% 
                summarise(n = n())) %>% 
    rename(r_est = chosen_trait_2) %>% 
    mutate(zr_est = r.to.zr(r_est),
           zr_var = zr.variance(n)) %>% 
    select(- c(4:6)) %>% 
    pivot_wider(names_from = sex,
                values_from = c(n,
                                zr_est,
                                zr_var)) %>% 
    mutate(delta_zr_est = zr_est_male - zr_est_female,
           delta_zr_var = zr_var_male + zr_var_female,
           delta_zr_upper = delta_zr_est + 
             qt(0.975, n_male + n_female - 2) * 
             sqrt(delta_zr_var),
           delta_zr_lower = delta_zr_est - 
             qt(0.975, n_male + n_female - 2) *
             sqrt(delta_zr_var))
  
  mlma_zr <-
    rma.mv(data = df_effects_cor,
           yi = delta_zr_est,
           V = delta_zr_var,
           test = "t",
           random = list(~ 1|phenotyping_center, 
                         ~ 1|strain_fig))
  
  df_model <- data.frame(delta_zr_est = mlma_zr$beta[1],
                         delta_zr_lower = mlma_zr$ci.lb,
                         delta_zr_upper = mlma_zr$ci.ub,
                         phenotyping_center = "Mean",
                         strain_fig = "ES")
  
  df_effects_cor %>% 
    bind_rows(df_model) %>% 
    mutate(centre_and_strain = factor(paste0(phenotyping_center,
                                             "\n",
                                             strain_fig))) %>% 
    mutate(centre_and_strain = factor(centre_and_strain,
                                      levels = c("Mean\nES",
                                                 rev(levels(centre_and_strain)[-5]))))
}

# visualisation functions ----
caterpillar.custom <- 
  function(chosen_trait = "fat_mass",
           measure = "KU_delta") {
    plot <-
      process.ind_effects(chosen_trait = chosen_trait,
                          measure = measure) %>% 
      ggplot(aes(y = centre_and_strain,
                 x = est,
                 xmax = upper,
                 xmin = lower,
                 shape = strain_fig,
                 col = phenotyping_center)) +
      geom_pointrange() +
      geom_vline(xintercept = 0,
                 linetype = "dotted") +
      theme_classic() +
      theme(legend.position = "none",
            axis.text.y = element_blank(),
            axis.title.y = element_blank(),
            plot.tag.position = c(0.15, 0.98))
    
    if (measure == "ROM") {
      plot +
        labs(x = "lnRR") +
        scale_x_continuous(limits = c(-0.51, 0.51),
                           breaks = c(-0.5, 0, 0.5)) +
        theme(axis.title.x = ggtext::element_markdown(face = "italic"))
    } else if (measure == "VR") {
      plot +
        labs(x = "lnVR") +
        scale_x_continuous(limits = c(-1, 1),
                           breaks = c(-1, 0, 1)) +
        theme(axis.title.x = ggtext::element_markdown(face = "italic"))
    } else if (measure == "SK_delta") {
      plot +
        labs(x = "&Delta;*sk*") +
        scale_x_continuous(limits = c(-2.1, 2.1),
                           breaks = c(-2, 0, 2)) +
        theme(axis.title.x = ggtext::element_markdown())
    } else if (measure == "KU_delta") {
      plot +
        labs(x = "&Delta;*ku*") +
        scale_x_continuous(limits = c(-15, 15),
                           breaks = c(-15, 0, 15)) +
        theme(axis.title.x = ggtext::element_markdown())
    }
  }

ridgeline.custom <- function(chosen_trait = "fat_mass") {
  df_raw %>% 
    filter(trait_name == chosen_trait,
           phenotyping_center %in% c("CCP-IMG",
                                     "HMGU",
                                     "JAX",
                                     "MRC H",
                                     "TCP")) %>% 
    add_row(phenotyping_center = "Mean",
            strain_fig = "ES") %>% 
    mutate(centre_and_strain = factor(paste0(phenotyping_center,
                                             "\n",
                                             strain_fig))) %>% 
    mutate(centre_and_strain = factor(centre_and_strain,
                                      levels = c("Mean\nES",
                                                 rev(levels(centre_and_strain)[-5]))),
           value_s = scale(value)) %>%
    ggplot(aes(x = value_s,
               y = centre_and_strain,
               fill = sex,
               linetype = sex)) +
    stat_slab(scale = 0.7, 
              alpha = 0.4,
              linewidth = 0.6,
              col = "black") +
    scale_fill_manual(values = c("white",
                                 "black")) +
    scale_linetype_manual(values = c("solid",
                                     "dashed")) +
    labs(x = paste0(str_to_sentence(str_replace_all(chosen_trait,
                                                    "_",
                                                    " ")),
                    "\n(scaled)"),
         y = "Phenotyping centre and mice strain") +
    theme_classic() +
    theme(legend.position = "none",
          axis.title.x = element_text(size = 12, 
                                      margin = margin(t = 0.2,
                                                      unit = "cm")),
          axis.title.y = element_text(size = 12, 
                                      margin = margin(r = 0.2,
                                                      unit = "cm")),
          axis.text.x = element_text(size = 10),
          axis.text.y = element_text(size = 10),
          plot.tag.position = c(0.53, 0.98))
}

cor.caterpillar.custom <- 
  function(chosen_trait_1 = "fat_mass",
           chosen_trait_2 = "heart_weight") {
    
    process.cor_effects(chosen_trait_1 = chosen_trait_1,
                        chosen_trait_2 = chosen_trait_2) %>% 
      ggplot(aes(y = centre_and_strain,
                 x = delta_zr_est,
                 xmax = delta_zr_upper,
                 xmin = delta_zr_lower,
                 shape = strain_fig,
                 col = phenotyping_center)) +
      geom_pointrange() +
      geom_vline(xintercept = 0,
                 linetype = "dotted") +
      labs(y = "Phenotyping centre and mice strain",
           x = "&Delta;*Zr*", 
           shape = "Strain") +
      scale_x_continuous(limits = c(-1, 1),
                         breaks = c(-1, 0, 1)) +
      theme_classic() +
      theme(legend.position = "none",
            axis.title.x = ggtext::element_markdown(size = 12, 
                                                    margin = margin(t = 0.2,
                                                                    unit = "cm")),
            axis.title.y = element_text(size = 12,
                                        margin = margin(r = - 0.1,
                                                        unit = "cm")),
            axis.text.x = element_text(size = 10),
            axis.text.y = element_text(size = 10),
            plot.tag.position = c(0.3, 0.99))
  }

cor.plot.custom <- 
  function(chosen_trait_1 = "fat_mass",
           chosen_trait_2 = "heart_weight",
           chosen_lims = c(-3, 5)) {
    df_cor <-
      df_raw %>% 
      filter(trait_name %in% c(chosen_trait_1,
                               chosen_trait_2), 
             phenotyping_center %in% c("CCP-IMG",
                                       "HMGU",
                                       "JAX",
                                       "MRC H",
                                       "TCP")) %>% 
      pivot_wider(id_cols = c(specimen_id,
                              strain_fig,
                              phenotyping_center,
                              sex),
                  names_from = trait_name) %>%
      clean_names() %>% 
      drop_na() %>% 
      mutate(centre_and_strain = factor(paste0(phenotyping_center,
                                               strain_fig))) %>% 
      mutate(centre_and_strain = factor(centre_and_strain,
                                        levels = rev(levels(centre_and_strain))),
             trait_1_s = scale(get(chosen_trait_1))[,1],
             trait_2_s = scale(get(chosen_trait_2))[,1])
    
    plot_list <- list()
    
    for (i in 1:length(levels(df_cor$centre_and_strain))) {
      level_i <- sort(levels(df_cor$centre_and_strain))[i]
      
      plot <-
        df_cor %>% 
        filter(centre_and_strain == level_i) %>% 
        ggplot(aes(x = trait_1_s,
                   y = trait_2_s,
                   shape = sex,
                   linetype = sex)) +
        geom_point(
          alpha = 0.008,
        ) +
        geom_abline(intercept = 0,
                    slope = 1,
                    linewidth = 0.5,
                    linetype = "dotted") +
        geom_smooth(method = "lm",
                    se = F,
                    col = "black") +
        scale_shape_manual(values = c(3, 4)) +
        scale_linetype_manual(values = c("solid",
                                         "dashed")) +
        scale_x_continuous(limits = chosen_lims) +
        scale_y_continuous(limits = chosen_lims) +
        labs(x = paste0(str_to_sentence(str_replace_all(chosen_trait_1, 
                                                        "_", 
                                                        " ")),
                        "\n(scaled)"),
             y = paste0(str_to_sentence(str_replace_all(chosen_trait_2, 
                                                        "_", 
                                                        " ")),
                        " (scaled)")) +
        theme_classic() +
        theme(legend.position = "none",
              plot.tag.position = c(0.05, 0.91),
              axis.title.x = element_text(size = 12, 
                                          margin = margin(t = 0.2,
                                                          unit = "cm")),
              axis.title.y = element_text(size = 12, 
                                          margin = margin(r = 0.2,
                                                          unit = "cm")),
              axis.text.x = element_text(size = 10),
              axis.text.y = element_text(size = 10))
      
      
      if (i != 6) {
        plot <-
          plot +
          theme(axis.title.x = element_blank(),
                axis.text.x = element_blank(),
                axis.line.x = element_blank(),
                axis.ticks.x = element_blank())
      }
      
      plot_list[[i]] <- plot
    }
    
    return(plot_list)
  }

5 Equations and custom functions to calculate effect sizes

5.1 Skewness

Following Pick et al. (2022).

\[ sk = \frac{\frac{1}{n} \sum_{i = 1}^{n}(x_{i} - \bar{x}) ^ 3}{[\frac{1}{n} \sum_{i = 1}^{n}(x - \bar{x}) ^ 2] ^ \frac{3}{2}} \frac{\sqrt{n (n - 1)}}{n - 2} \] \[ s^2_{sk} = \frac{6n(n - 1)}{(n - 2)(n + 1)(n + 3)} \]

\[ \Delta sk = sk_{1} - sk_{2} \]

\[ s^2_{\Delta sk} = s^2_{sk_1} + s^2_{sk_2} - 2 \rho_{sk} s_{sk_1} s_{sk_2} \]

5.2 Kurtosis

\[ ku = \frac{n (n + 1) (n - 1)}{(n - 2)(n - 3)} \frac{\sum_{i = 1}^{n}(x_{i} - \bar{x}) ^ 4} {[\sum_{i = 1}^{n}(x_{i} - \bar{x}) ^ 2]^ 2} - \frac{3(n - 1) ^ 2}{(n - 2)(n - 3)} \] \[ s^2_{ku} = \frac{24 n (n - 1) ^ 2}{(n - 3)(n - 2)(n + 3)(n + 5)} \]

\[ \Delta ku = ku_{1} - ku_{2} \]

\[ s^2_{\Delta ku} = s^2_{ku_1} + s^2_{ku_2} - 2 \rho_{ku} s_{ku_1} s_{ku_2} \]

5.3 Zr

\[ Zr = \frac{ln(\frac{1 + r}{1 - r})}{2} \]

\[ s^2_{Zr} = \frac{1}{n - 3} \] \[ \Delta Zr = Zr_{1} - Zr_{2} \]

\[ s^2_{\Delta Zr} = s^2_{Zr_1} + s^2_{Zr_2} -2 \rho_{Zr} s_{Zr_1} s_{Zr_2} \]

6 Data loading and preparation

We use data from the International Mouse Phenotyping Consortium (IMPC, version 18.0; Dickinson et al., 2016; http://www.mousephenotype.org/).

Code
# raw data ----
df_raw <- 
  read_csv("mice_data_sample.csv") %>% 
  # small adjustments to make plots more readable:
  mutate(phenotyping_center = 
           ifelse(phenotyping_center == "MRC Harwell",
                  "MRC H",
                  phenotyping_center),
         strain_fig = case_when(strain_accession_id == "MGI:2159965" ~ 
                                  "N",
                                strain_accession_id == "MGI:2683688" ~ 
                                  "NCrl",
                                strain_accession_id == "MGI:2164831" ~ 
                                  "NTac",
                                strain_accession_id == "MGI:3056279" ~ 
                                  "NJ",
                                strain_accession_id == "MGI:2160139" ~ 
                                  "NJcl"))

df_meta_analysed <-
  df_raw %>% 
  group_by(sex,
           trait_name,
           phenotyping_center,
           strain_fig) %>% 
  summarize(mean = mean(value,
                        na.rm = T),
            sd = sd(value,
                    na.rm = T),
            n = n(),
            SK_est = calc.skewness(value),
            SK_var = calc.skewness(value, output = "var"),
            KU_est = calc.kurtosis(value),
            KU_var = calc.kurtosis(value, output = "var")) %>% 
  pivot_wider(id_cols = c(trait_name,
                          phenotyping_center,
                          strain_fig),
              names_from = sex,
              values_from = c(mean:KU_var)) %>% 
  mutate(SK_delta_est = SK_est_male - SK_est_female,
         SK_delta_var = SK_var_male + SK_var_female,
         KU_delta_est = KU_est_male - KU_est_female,
         KU_delta_var = KU_var_male + KU_var_female) %>% 
  bind_cols(calc.effect(., m = "ROM")) %>% # lnRR
  bind_cols(calc.effect(., m = "CVR")) %>% # lnCVR
  bind_cols(calc.effect(., m = "VR")) %>% # lnVR
  filter(!is.na(CVR_est)) %>% 
  mutate(n_total = n_female + n_male,
         prop_females = n_female / (n_female + n_male)) %>% 
  select(trait_name,
         phenotyping_center,
         strain_fig,
         n_total,
         prop_females,
         ROM_est,
         ROM_var,
         CVR_est,
         CVR_var,
         VR_est,
         VR_var,
         SK_delta_est,
         SK_delta_var,
         KU_delta_est,
         KU_delta_var) %>% 
  mutate(ROM_upper = ROM_est + qt(0.975, 
                                  n_total - 1) * sqrt(ROM_var),
         ROM_lower = ROM_est - qt(0.975, 
                                  n_total - 1) * sqrt(ROM_var),
         CVR_upper = CVR_est + qt(0.975, 
                                  n_total - 1) * sqrt(CVR_var),
         CVR_lower = CVR_est - qt(0.975, 
                                  n_total - 1) * sqrt(CVR_var),
         VR_upper = VR_est + qt(0.975, 
                                n_total - 1) * sqrt(VR_var),
         VR_lower = VR_est - qt(0.975, 
                                n_total - 1) * sqrt(VR_var),
         SK_delta_upper = SK_delta_est + qt(0.975, 
                                            n_total - 1) * sqrt(SK_delta_var),
         SK_delta_lower = SK_delta_est - qt(0.975, 
                                            n_total - 1) * sqrt(SK_delta_var),
         KU_delta_upper = KU_delta_est + qt(0.975, 
                                            n_total - 1) * sqrt(KU_delta_var),
         KU_delta_lower = KU_delta_est - qt(0.975, 
                                            n_total - 1) * sqrt(KU_delta_var))

7 Meta-analytical models

We then use the data from multiple phenotyping centres and mice strains to calculate average effect sizes (\(\Delta sk\), \(\Delta ku\), and \(\Delta Zr\)).

7.1 Single variable effect sizes

Code
map2_dfr(.x = rep(c("fat_mass",
                    "heart_weight",
                    "glucose",
                    "total_cholesterol"),
                  each = 4),
         .y = rep(c("ROM",
                    "VR",
                    "SK_delta",
                    "KU_delta"), 
                  4),
         .f = process.ind_effects) %>% 
  mutate(est_type = case_when(est_type == "ROM" ~ "lnRR",
                              est_type == "VR" ~ "lnVR",
                              est_type == "SK_delta" ~ "delta_sk",
                              est_type == "KU_delta" ~ "delta_ku")) %>% 
  datatable(.,
            extensions = "Buttons",
            rownames = FALSE)

7.2 Correlational effect sizes

Code
map2_dfr(.x = c("fat_mass",
                "glucose"),
         .y = c("heart_weight",
                "total_cholesterol"),
         .f = process.cor_effects) %>% 
  mutate(relationship = rep(c("fat mass and heart weight",
                              "glucose and total cholesterol"),
                            each = 7)) %>% 
  relocate(relationship) %>%  
  datatable(.,
            extensions = "Buttons",
            rownames = FALSE)
## Warning: Using an external vector in selections was deprecated in tidyselect 1.1.0.
## ℹ Please use `all_of()` or `any_of()` instead.
##   # Was:
##   data %>% select(chosen_trait_2)
## 
##   # Now:
##   data %>% select(all_of(chosen_trait_2))
## 
## See <https://tidyselect.r-lib.org/reference/faq-external-vector.html>.

8 Visualisations

Code
## figure_2 ----
list_figure_2 <- list()
list_figure_2[[1]] <- ridgeline.custom("fat_mass")
list_figure_2[2:5] <- map2(.x = rep("fat_mass", 4),
                           .y = c("ROM",
                                  "VR",
                                  "SK_delta",
                                  "KU_delta"),
                           .f = caterpillar.custom)
list_figure_2[[6]] <- ridgeline.custom("heart_weight")
list_figure_2[7:10] <- map2(.x = rep("heart_weight", 4),
                            .y = c("ROM",
                                   "VR",
                                   "SK_delta",
                                   "KU_delta"),
                            .f = caterpillar.custom)

(figure_2 <-
    list_figure_2 %>% 
    wrap_plots(ncol = 5) +
    plot_annotation(tag_levels = "A"))
## Warning: Removed 1 row containing missing values or values outside the scale range
## (`stat_slabinterval()`).
## Removed 1 row containing missing values or values outside the scale range
## (`stat_slabinterval()`).

Code

## figure_3 ----
list_figure_3 <- list()
list_figure_3[1:6] <- cor.plot.custom(chosen_trait_1 = "fat_mass",
                                      chosen_trait_2 = "heart_weight")
list_figure_3[[7]] <- cor.caterpillar.custom(chosen_trait_1 = "fat_mass",
                                             chosen_trait_2 = "heart_weight")

list_figure_3[8:13] <- cor.plot.custom(chosen_trait_1 = "glucose",
                                       chosen_trait_2 = "total_cholesterol")

list_figure_3[[14]] <- cor.caterpillar.custom(chosen_trait_1 = "glucose",
                                              chosen_trait_2 = "total_cholesterol")
(figure_3 <-
    list_figure_3 %>% 
    wrap_plots() +
    plot_layout(design = layout_2,
                heights = c(rep(1, 6), 0.6),
                widths = c(rep(0.23, 2), 0.02, rep(0.23, 2)),
                axes = "collect",
                guides = "collect") +
    plot_annotation(tag_levels = list(c("A", 
                                        rep("", 
                                            5), 
                                        "B",
                                        "C",
                                        rep("", 
                                            5),
                                        "D"))))
## Warning: Removed 4 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 4 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 1 row containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 1 row containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 3 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 3 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 27 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 27 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 3 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 3 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 25 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 25 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 3 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 3 rows containing missing values or values outside the scale range
## (`geom_point()`).
## Warning: Removed 2 rows containing non-finite outside the scale range
## (`stat_smooth()`).
## Warning: Removed 2 rows containing missing values or values outside the scale range
## (`geom_point()`).

Code

## figure_4 ----
list_figure_4 <- list()
list_figure_4[[1]] <- ridgeline.custom("glucose")
list_figure_4[2:5] <- map2(.x = rep("glucose", 4),
                           .y = c("ROM",
                                  "VR",
                                  "SK_delta",
                                  "KU_delta"),
                           .f = caterpillar.custom)
list_figure_4[[6]] <- ridgeline.custom("total_cholesterol")
list_figure_4[7:10] <- map2(.x = rep("total_cholesterol", 4),
                            .y = c("ROM",
                                   "VR",
                                   "SK_delta",
                                   "KU_delta"),
                            .f = caterpillar.custom)

(figure_4 <-
    list_figure_4 %>% 
    wrap_plots(ncol = 5) +
    plot_annotation(tag_levels = "A"))
## Warning: Removed 1 row containing missing values or values outside the scale range
## (`stat_slabinterval()`).
## Warning: Removed 1 row containing missing values or values outside the scale range
## (`stat_slabinterval()`).

9 Software and package versions

Code
sessionInfo() %>% 
  pander()

R version 4.4.2 (2024-10-31 ucrt)

Platform: x86_64-w64-mingw32/x64

locale: LC_COLLATE=English_Australia.utf8, LC_CTYPE=English_Australia.utf8, LC_MONETARY=English_Australia.utf8, LC_NUMERIC=C and LC_TIME=English_Australia.utf8

attached base packages: stats, graphics, grDevices, utils, datasets, methods and base

other attached packages: lubridate(v.1.9.3), forcats(v.1.0.0), stringr(v.1.5.1), dplyr(v.1.1.4), purrr(v.1.0.2), readr(v.2.1.5), tidyr(v.1.3.1), tibble(v.3.2.1), ggplot2(v.3.5.1), tidyverse(v.2.0.0), patchwork(v.1.3.0), pander(v.0.6.6), metafor(v.4.6-0), numDeriv(v.2016.8-1.1), metadat(v.1.2-0), Matrix(v.1.7-1), janitor(v.2.2.0), here(v.1.0.1), ggtext(v.0.1.2), ggdist(v.3.3.2), DT(v.0.33), corrr(v.0.4.4) and pacman(v.0.5.1)

loaded via a namespace (and not attached): gtable(v.0.3.6), bslib(v.0.8.0), xfun(v.0.49), htmlwidgets(v.1.6.4), lattice(v.0.22-6), mathjaxr(v.1.6-0), tzdb(v.0.4.0), crosstalk(v.1.2.1), vctrs(v.0.6.5), tools(v.4.4.2), generics(v.0.1.3), parallel(v.4.4.2), pkgconfig(v.2.0.3), distributional(v.0.5.0), lifecycle(v.1.0.4), compiler(v.4.4.2), farver(v.2.1.2), munsell(v.0.5.1), snakecase(v.0.11.1), sass(v.0.4.9), htmltools(v.0.5.8.1), yaml(v.2.3.10), jquerylib(v.0.1.4), pillar(v.1.10.0), crayon(v.1.5.3), cachem(v.1.1.0), nlme(v.3.1-166), commonmark(v.1.9.2), tidyselect(v.1.2.1), digest(v.0.6.37), stringi(v.1.8.4), splines(v.4.4.2), labeling(v.0.4.3), rprojroot(v.2.0.4), fastmap(v.1.2.0), grid(v.4.4.2), colorspace(v.2.1-1), cli(v.3.6.3), magrittr(v.2.0.3), withr(v.3.0.2), scales(v.1.3.0), bit64(v.4.5.2), timechange(v.0.3.0), rmarkdown(v.2.29), bit(v.4.5.0), hms(v.1.1.3), evaluate(v.1.0.1), knitr(v.1.49), mgcv(v.1.9-1), markdown(v.1.13), rlang(v.1.1.4), gridtext(v.0.1.5), Rcpp(v.1.0.13-1), glue(v.1.8.0), xml2(v.1.3.6), rstudioapi(v.0.17.1), vroom(v.1.6.5), jsonlite(v.1.8.9) and R6(v.2.5.1)