Rationale


The purpose of this experiment was to find out whether being exposed to violent or aggressive behavior would cause students to act more aggressively afterward, even in situations that weren’t related to the exposure.

Hypothesis

Students who played the violent game showed the most aggressive behavior after they were done playing — even if that was in the interim and didn’t create long lasting effects.

Variables & method

A total of 135 fifth-graders from a large suburban elementary school took part in the study. The students were randomly divided into three groups of 45. About 30 minutes before recess, each group did a different activity.

The first group played a math game called Exponent Fighter. In this game, every time a player solved an exponent problem correctly, their character got to punch an on-screen opponent. If they got the problem wrong, the opponent punched their character instead.

The second group played another math game called Exponent Builder. This version had the same kinds of math problems, but instead of fighting, players earned blocks to build a structure that helped their character reach a higher platform.

The third group didn’t play a game at all. Instead, they worked on an art project where they used a color wheel to choose a color scheme for a stencil painting.

After the 30-minute activity, all the students went outside for a 30-minute recess. During recess, trained researchers observed and recorded how much time each student spent behaving aggressively. Aggression could be either verbal (like taunting or threatening) or physical (like pushing or grabbing). Serious behaviors that violated school rules were handled by teachers and weren’t included in the data.

Because there were three different activity groups, a one-way ANOVA was used to compare the average number of minutes each group spent acting aggressively during recess. The box plot showed that the means and medians for all three groups were fairly close, which meant the data weren’t skewed by outliers.

Results

Students who played the violent game showed the most aggressive behavior.

Students who played the nonviolent game showed moderate levels.

Students who did the art project showed the least aggression.

In other words, the group exposed to the violent game acted aggressively for almost twice as long as either of the other groups.

Overall, the results suggest that violent game elements, even in an educational setting, can lead to more aggressive behavior right afterward.

Descriptive Statistics by Group
IV count mean sd min max
Art project 45 4.96 1.04 2.3 7.3
Nonviolent game 45 5.86 1.06 3.6 8.4
Violent game 45 10.75 1.00 8.5 12.8
Shapiro-Wilk Normality Test by Group
IV W_statistic p_value
Art project 0.99 0.923
Nonviolent game 0.98 0.594
Violent game 0.98 0.699
Note. If any p-value figures are 0.05 or less, if one or more group distributions appear non-normal, and any group sizes are less than 40, consider using the Kruskal-Wallis and Post-hoc Dunn’s Test results instead of the ANOVA and Tukey HSD Post-hoc results.
ANOVA Test Results
Statistic df df_resid p_value
420.86 2 87.94717 < .001
Tukey HSD Post-hoc Results
Comparison diff lwr upr p adj
Nonviolent game-Art project 0.90 0.38 1.42 < .001
Violent game-Art project 5.79 5.27 6.30 < .001
Violent game-Nonviolent game 4.89 4.37 5.40 < .001
Kruskal-Wallis Test Results
Statistic df p_value
95.23 2 < .001
Post-hoc Dunn’s Test Results
Comparison Z P.unadj P.adj
Art project - Nonviolent game -2.42 0.016 0.047
Art project - Violent game -9.40 < .001 < .001
Nonviolent game - Violent game -6.98 < .001 < .001
 
# ============================================================
#  Setup: Install and Load Required Packages
# ============================================================
if (!require("tidyverse")) install.packages("tidyverse")
if (!require("gt")) install.packages("gt")
if (!require("gtExtras")) install.packages("gtExtras")
if (!require("FSA")) install.packages("FSA")
if (!require("plotly")) install.packages("plotly")

library(tidyverse)
library(gt)
library(gtExtras)
library(FSA)
library(plotly)

options(scipen = 999) # suppress scientific notation

# ============================================================
#  Step 1: Load Data
# ============================================================
mydata <- read.csv("Priming.csv") # <-- Edit YOURFILENAME.csv

# Specify DV and IV (edit column names here)
mydata$DV <- mydata$Value
mydata$IV <- mydata$Group

# ============================================================
#  Step 2: Visualize Group Distributions (Interactive)
# ============================================================
# Compute group means
group_means <- mydata %>%
  group_by(IV) %>%
  summarise(mean_value = mean(DV), .groups = "drop")

# Interactive plot (boxplot + group means)
box_plot <- plot_ly() %>%
  # Boxplot trace
  add_trace(
    data = mydata,
    x = ~IV, y = ~DV,
    type = "box",
    boxpoints = "outliers",   # only applies here
    marker = list(color = "red", size = 4),  # outlier style
    line = list(color = "black"),
    fillcolor = "royalblue",
    name = ""
  ) %>%
  # Group means (diamonds)
  add_trace(
    data = group_means,
    x = ~IV, y = ~mean_value,
    type = "scatter", mode = "markers",
    marker = list(
      symbol = "diamond", size = 9,
      color = "black", line = list(color = "white", width = 1)
    ),
    text = ~paste0("Mean = ", round(mean_value, 2)),
    hoverinfo = "text",
    name = "Group Mean"
  ) %>%
  layout(
    title = "Interactive Group Distributions with Means",
    xaxis = list(title = "Independent Variable (IV)"),
    yaxis = list(title = "Dependent Variable (DV)"),
    showlegend = FALSE
  )

# ============================================================
#  Step 3: Descriptive Statistics by Group
# ============================================================
desc_stats <- mydata %>%
  group_by(IV) %>%
  summarise(
    count = n(),
    mean = mean(DV, na.rm = TRUE),
    sd   = sd(DV, na.rm = TRUE),
    min  = min(DV, na.rm = TRUE),
    max  = max(DV, na.rm = TRUE)
  )

desc_table <- desc_stats %>%
  mutate(across(where(is.numeric), ~round(.x, 2))) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "Descriptive Statistics by Group")

# ============================================================
#  Step 4: Test Normality (Shapiro-Wilk)
# ============================================================
shapiro_results <- mydata %>%
  group_by(IV) %>%
  summarise(
    W_statistic = shapiro.test(DV)$statistic,
    p_value = shapiro.test(DV)$p.value
  )

shapiro_table <- shapiro_results %>%
  mutate(
    W_statistic = round(W_statistic, 2),
    p_value = ifelse(p_value < .001, "< .001", sprintf("%.3f", p_value))
  ) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "Shapiro-Wilk Normality Test by Group") %>%
  tab_source_note(
    source_note = "Note. If any p-value figures are 0.05 or less, if one or more group distributions appear non-normal, and any group sizes are less than 40, consider using the Kruskal-Wallis and Post-hoc Dunn’s Test results instead of the ANOVA and Tukey HSD Post-hoc results."
  )

# ============================================================
#  Step 5a: Non-Parametric Test (Kruskal-Wallis + Dunn)
# ============================================================
kruskal_res <- kruskal.test(DV ~ IV, data = mydata)

kruskal_table <- data.frame(
  Statistic = round(kruskal_res$statistic, 2),
  df = kruskal_res$parameter,
  p_value = ifelse(kruskal_res$p.value < .001, "< .001",
                   sprintf("%.3f", kruskal_res$p.value))
) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "Kruskal-Wallis Test Results")

dunn_res <- dunnTest(DV ~ IV, data = mydata, method = "bonferroni")$res

dunn_table <- dunn_res %>%
  mutate(
    Z = round(Z, 2),
    P.unadj = ifelse(P.unadj < .001, "< .001", sprintf("%.3f", P.unadj)),
    P.adj   = ifelse(P.adj < .001, "< .001", sprintf("%.3f", P.adj))
  ) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "Post-hoc Dunn’s Test Results")

# ============================================================
#  Step 5b: Parametric Test (ANOVA + Tukey)
# ============================================================
anova_res <- oneway.test(DV ~ IV, data = mydata, var.equal = FALSE)

anova_table <- data.frame(
  Statistic = round(anova_res$statistic, 2),
  df = anova_res$parameter[1],
  df_resid = anova_res$parameter[2],
  p_value = ifelse(anova_res$p.value < .001, "< .001",
                   sprintf("%.3f", anova_res$p.value))
) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "ANOVA Test Results")

anova_model <- aov(DV ~ IV, data = mydata)
tukey_res <- TukeyHSD(anova_model)$IV %>% as.data.frame()

tukey_table <- tukey_res %>%
  rownames_to_column("Comparison") %>%
  mutate(
    diff = round(diff, 2),
    lwr = round(lwr, 2),
    upr = round(upr, 2),
    `p adj` = ifelse(`p adj` < .001, "< .001", sprintf("%.3f", `p adj`))
  ) %>%
  gt() %>%
  gt_theme_538() %>%
  tab_header(title = "Tukey HSD Post-hoc Results")

# ============================================================
#  Step 6: Display Key Results
# ============================================================
# Interactive box plot
box_plot

# Tables
desc_table
shapiro_table
anova_table
tukey_table
kruskal_table
dunn_table