Project 2: Comparing IMDb Ratings Across Different Genres

Objective

In this lab session, we will analyze IMDb movie ratings across different genres to determine if there are significant differences in ratings. We will use a sample movie dataset to:

Perform data wrangling.
Conduct exploratory data analysis (EDA).
Visualize the distribution of ratings across genres.
Perform ANOVA to test for significant differences in mean ratings.
Check assumptions of normality and homogeneity of variance.

Step 1: Load Libraries and Dataset

# Load necessary libraries
library(tidyverse)

# Load the dataset
imdb_data <- read.csv("imdb_top_1000.csv")

# Display the first few rows
head(imdb_data)

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Step 2: Data Cleaning

Extract the primary genre and handle missing data.

# Extract the primary genre (first genre listed)
imdb_data <- imdb_data %>%
  mutate(Primary_Genre = sapply(strsplit(as.character(Genre), ","), `[`, 1))

# Convert Primary_Genre and IMDB_Rating to appropriate data types
imdb_data$Primary_Genre <- as.factor(imdb_data$Primary_Genre)
imdb_data$IMDB_Rating <- as.numeric(imdb_data$IMDB_Rating)

# Remove rows with missing ratings or genres
imdb_data <- na.omit(imdb_data[, c("Primary_Genre", "IMDB_Rating")])

Step 3: Perform ANOVA

# One-way ANOVA
anova_result <- aov(IMDB_Rating ~ Primary_Genre, data = imdb_data)

# Display ANOVA summary
summary(anova_result)

##                Df Sum Sq Mean Sq F value Pr(>F)  
## Primary_Genre  13   1.65 0.12724   1.692 0.0574 .
## Residuals     986  74.17 0.07522                 
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Step 4: Post-Hoc Analysis

If the ANOVA result is significant, perform a Tukey’s HSD test to identify which genres differ.

# Tukey's HSD test
tukey_result <- TukeyHSD(anova_result)

# Display the results
print(tukey_result)

##   Tukey multiple comparisons of means
##     95% family-wise confidence level
## 
## Fit: aov(formula = IMDB_Rating ~ Primary_Genre, data = imdb_data)
## 
## $Primary_Genre
##                              diff           lwr        upr     p adj
## Adventure-Action    -1.191860e-02 -0.1413491135 0.11751190 1.0000000
## Animation-Action    -1.893080e-02 -0.1426730262 0.10481143 0.9999997
## Biography-Action    -1.078224e-02 -0.1316340990 0.11006962 1.0000000
## Comedy-Action       -4.812828e-02 -0.1502495083 0.05399294 0.9500042
## Crime-Action         6.740383e-02 -0.0461281533 0.18093580 0.7701356
## Drama-Action         8.020842e-03 -0.0807784568 0.09682014 1.0000000
## Family-Action       -1.494186e-01 -0.8052128780 0.50637567 0.9999654
## Fantasy-Action       5.058140e-02 -0.6052128780 0.70637567 1.0000000
## Film-Noir-Action     1.724806e-02 -0.5197421758 0.55423830 1.0000000
## Horror-Action       -4.032770e-02 -0.3270999932 0.24644460 0.9999999
## Mystery-Action       2.558140e-02 -0.2497313278 0.30089412 1.0000000
## Thriller-Action     -1.494186e-01 -1.0741828822 0.77534567 0.9999994
## Western-Action       4.005814e-01 -0.0657926057 0.86695540 0.1845735
## Animation-Adventure -7.012195e-03 -0.1559343813 0.14190999 1.0000000
## Biography-Adventure  1.136364e-03 -0.1453929867 0.14766571 1.0000000
## Comedy-Adventure    -3.620968e-02 -0.1677179425 0.09529859 0.9997063
## Crime-Adventure      7.932243e-02 -0.0612307241 0.21987558 0.8278322
## Drama-Adventure      1.993945e-02 -0.1015142253 0.14139312 0.9999993
## Family-Adventure    -1.375000e-01 -0.7985081753 0.52350818 0.9999881
## Fantasy-Adventure    6.250000e-02 -0.5985081753 0.72350818 1.0000000
## Film-Noir-Adventure  2.916667e-02 -0.5141787064 0.57251204 1.0000000
## Horror-Adventure    -2.840909e-02 -0.3269120718 0.27009389 1.0000000
## Mystery-Adventure    3.750000e-02 -0.2500113467 0.32501135 1.0000000
## Thriller-Adventure  -1.375000e-01 -1.0659689806 0.79096898 0.9999998
## Western-Adventure    4.125000e-01 -0.0611775146 0.88617751 0.1675499
## Biography-Animation  8.148559e-03 -0.1333814115 0.14967853 1.0000000
## Comedy-Animation    -2.919748e-02 -0.1551113646 0.09671640 0.9999576
## Crime-Animation      8.633463e-02 -0.0489985604 0.22166781 0.6697503
## Drama-Animation      2.695164e-02 -0.0884211297 0.14232441 0.9999538
## Family-Animation    -1.304878e-01 -0.7904057466 0.52943014 0.9999935
## Fantasy-Animation    6.951220e-02 -0.5904057466 0.72943014 1.0000000
## Film-Noir-Animation  3.617886e-02 -0.5058396586 0.57819738 1.0000000
## Horror-Animation    -2.139690e-02 -0.3174778165 0.27468402 1.0000000
## Mystery-Animation    4.451220e-02 -0.2404836933 0.32950808 0.9999996
## Thriller-Animation  -1.304878e-01 -1.0581809276 0.79720532 0.9999999
## Western-Animation    4.195122e-01 -0.0526427263 0.89166712 0.1444755
## Comedy-Biography    -3.734604e-02 -0.1604205662 0.08572848 0.9991631
## Crime-Biography      7.818607e-02 -0.0545094651 0.21088160 0.7794809
## Drama-Biography      1.880308e-02 -0.0934640509 0.13107022 0.9999991
## Family-Biography    -1.386364e-01 -0.7980184401 0.52074571 0.9999865
## Fantasy-Biography    6.136364e-02 -0.5980184401 0.72074571 1.0000000
## Film-Noir-Biography  2.803030e-02 -0.5133356632 0.56939627 1.0000000
## Horror-Biography    -2.954545e-02 -0.3244300838 0.26533917 1.0000000
## Mystery-Biography    3.636364e-02 -0.2473892304 0.32011650 1.0000000
## Thriller-Biography  -1.386364e-01 -1.0659483731 0.78867565 0.9999998
## Western-Biography    4.113636e-01 -0.0600420305 0.88276930 0.1651001
## Crime-Comedy         1.155321e-01 -0.0003630061 0.23142722 0.0516588
## Drama-Comedy         5.614912e-02 -0.0356521974 0.14795044 0.7310799
## Family-Comedy       -1.012903e-01 -0.7574978325 0.55491719 0.9999997
## Fantasy-Comedy       9.870968e-02 -0.5574978325 0.75491719 0.9999998
## Film-Noir-Comedy     6.537634e-02 -0.4721184770 0.60287117 1.0000000
## Horror-Comedy        7.800587e-03 -0.2799154503 0.29551662 1.0000000
## Mystery-Comedy       7.370968e-02 -0.2025859300 0.35000528 0.9997927
## Thriller-Comedy     -1.012903e-01 -1.0263476917 0.82376705 1.0000000
## Western-Comedy       4.487097e-01 -0.0182452198 0.91566457 0.0742746
## Drama-Crime         -5.938298e-02 -0.1637297510 0.04496378 0.8190955
## Family-Crime        -2.168224e-01 -0.8749022589 0.44125740 0.9980345
## Fantasy-Crime       -1.682243e-02 -0.6749022589 0.64125740 1.0000000
## Film-Noir-Crime     -5.015576e-02 -0.5899348366 0.48962331 1.0000000
## Horror-Crime        -1.077315e-01 -0.3996926195 0.18422958 0.9939984
## Mystery-Crime       -4.182243e-02 -0.3225358567 0.23889100 0.9999998
## Thriller-Crime      -2.168224e-01 -1.1432089051 0.70956405 0.9999528
## Western-Crime        3.331776e-01 -0.1364048416 0.80275998 0.4916256
## Family-Drama        -1.574394e-01 -0.8117061096 0.49682722 0.9999351
## Fantasy-Drama        4.256055e-02 -0.6117061096 0.69682722 1.0000000
## Film-Noir-Drama      9.227220e-03 -0.5258963666 0.54435081 1.0000000
## Horror-Drama        -4.834854e-02 -0.3316100567 0.23491298 0.9999989
## Mystery-Drama        1.756055e-02 -0.2540933314 0.28921444 1.0000000
## Thriller-Drama      -1.574394e-01 -1.0811210510 0.76624216 0.9999989
## Western-Drama        3.925606e-01 -0.0716629341 0.85678404 0.2049787
## Fantasy-Family       2.000000e-01 -0.7220876749 1.12208767 0.9999805
## Film-Noir-Family     1.666667e-01 -0.6750803659 1.00841370 0.9999934
## Horror-Family        1.090909e-01 -0.5997235249 0.81790534 0.9999997
## Mystery-Family       1.750000e-01 -0.5292560946 0.87925609 0.9999065
## Thriller-Family     -6.217249e-15 -1.1293221507 1.12932215 1.0000000
## Western-Family       5.500000e-01 -0.2485513509 1.34855135 0.5436231
## Film-Noir-Fantasy   -3.333333e-02 -0.8750803659 0.80841370 1.0000000
## Horror-Fantasy      -9.090909e-02 -0.7997235249 0.61790534 1.0000000
## Mystery-Fantasy     -2.500000e-02 -0.7292560946 0.67925609 1.0000000
## Thriller-Fantasy    -2.000000e-01 -1.3293221507 0.92932215 0.9999983
## Western-Fantasy      3.500000e-01 -0.4485513509 1.14855135 0.9720414
## Horror-Film-Noir    -5.757576e-02 -0.6581673730 0.54301586 1.0000000
## Mystery-Film-Noir    8.333333e-03 -0.5868717014 0.60353837 1.0000000
## Thriller-Film-Noir  -1.666667e-01 -1.2314018012 0.89806847 0.9999996
## Western-Film-Noir    3.833333e-01 -0.3209227612 1.08758943 0.8622025
## Mystery-Horror       6.590909e-02 -0.3189920243 0.45081021 0.9999988
## Thriller-Horror     -1.090909e-01 -1.0721800752 0.85399826 1.0000000
## Western-Horror       4.409091e-01 -0.0974741201 0.97929230 0.2504262
## Thriller-Mystery    -1.750000e-01 -1.1347392806 0.78473928 0.9999975
## Western-Mystery      3.750000e-01 -0.1573675673 0.90736757 0.5043727
## Western-Thriller     5.500000e-01 -0.4809253611 1.58092536 0.8789044

Step 5: Interpretation

ANOVA Output: If the p-value is less than the significance level (e.g., 0.05), it indicates that there is a statistically significant difference in IMDb ratings between at least two genres.
Tukey’s HSD Test: The test will show which pairs of genres have significant differences in mean IMDb ratings.

Step 6: Visualization

# Boxplot of IMDb Ratings by Primary Genre
ggplot(imdb_data, aes(x = Primary_Genre, y = IMDB_Rating, fill = Primary_Genre)) +
  geom_boxplot() +
  theme_minimal() +
  labs(
    title = "Boxplot of IMDb Ratings by Genre",
    x = "Primary Genre",
    y = "IMDb Rating"
  ) +
  theme(axis.text.x = element_text(angle = 45, hjust = 1))