Submitted:
05 December 2025
Posted:
10 December 2025
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Abstract
Keywords:
1. Introduction
1.1. Research Questions
- RQ1: Does average sentiment about Apple in Reddit finance communities differ before versus after the 2020 product launch?
- RQ2: Does user engagement with Apple-related comments (upvotes) differ between the two periods?
- RQ3: How are sentiment, text length, and engagement related to each other?
- RQ4 (Exploratory): How does a transformer-based sentiment classifier compare to VADER on this domain, using a labeled subset of comments?
1.2. Social Media Sentiment and Financial Behavior
1.3. Reddit Communities and Investor Psychology
1.4. Brand Perception and Product Launch Events
1.5. Sentiment Analysis Methods
2. Methods
2.1. Data
- Subreddit name (stored as subreddit.name, later renamed Platform)
- Unix timestamp of the comment (created_utc)
- Author identifier (id, later treated as User)
- Raw comment body (body, later renamed Text)
- Score, which represents the net upvotes assigned by other users
- word_length – total number of whitespace-separated tokens in each comment
- char_length – total number of characters in the cleaned comment text
2.2. Predictors
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Sentiment score (VADER compound).Sentiment was quantified using the VADER (Valence Aware Dictionary for sEntiment Reasoning) model (Hutto & Gilbert, 2014), which is widely used for short, informal social media text. For each comment, the VADER analyzer produced a compound score ranging from −1 (extremely negative) to +1 (extremely positive). This continuous variable served as the main predictor for emotional tone.
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Text length.Two continuous measures captured the length of each comment:
- word_length (number of words)
- char_length (number of characters) These variables were used both descriptively and in correlation analyses to examine whether longer comments tended to be more emotional or received more engagement.
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Period.The binary Period variable (Before vs. After) acted as the key grouping factor for comparing sentiment and engagement surrounding the 2020 product launch. Because no random assignment was possible, Period functions as a quasi-experimental factor indicating temporal proximity to the launch, not a true experimental manipulation.
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Platform.Although not a main predictor in the statistical tests reported here, the Platform variable (subreddit name) was used descriptively to understand where most Apple-related discussion occurred (e.g., r/wallstreetbets vs. r/stocks).
2.3. Outcome Measures
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Sentiment (RQ1).For RQ1, the outcome was the VADER compound score, treated as a continuous variable. The main comparison was the difference in mean sentiment between the Before and After periods.
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Engagement (RQ2).For RQ2, the outcome was Upvotes, the Reddit “score” variable, which reflects the net number of upvotes minus downvotes a comment received. Upvotes served as a proxy for community engagement or perceived value of the comment.
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Correlational structure (RQ3).For RQ3, the outcomes of interest were the pairwise relationships among sentiment, engagement, and text length. Specifically, Pearson correlations were computed among compound sentiment, Upvotes, word_length, and char_length to understand how emotional tone and comment length relate to visibility and engagement.
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Model comparison (RQ4).For RQ4, the intended outcome was classification performance of a modern transformer model compared with VADER on a labeled subset of comments. Due to hardware limitations, this step remained exploratory and conceptual rather than fully quantitative. However, the study still describes how a transformer model could be fine-tuned on Apple-related comments in future work.
2.4. Data Analytic Plan
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Data loading and basic preprocessing.The raw CSV file was loaded into a pandas DataFrame. The created_utc field was converted from Unix time to a timezone-aware Timestamp column. Core variables were renamed for clarity: subreddit.name → Platform, body → Text, score → Upvotes, and id → User. A Period flag (Before vs. After) was computed based on the 2020 launch date.
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Text cleaning.Although Reddit comments contain substantial informal content, minimal cleaning was applied to preserve their original meaning. URLs, Markdown links, and obvious formatting artifacts were removed. Basic normalization (e.g., stripping extra whitespace) was performed, but emojis, punctuation, and capitalization were left intact because VADER is trained to interpret such cues.
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Feature engineering.Text-length variables were computed by counting whitespace-separated tokens (word_length) and characters (char_length) in each cleaned comment. These variables were later used for descriptive statistics, distribution plots, and correlations.
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Sentiment scoring.The NLTK implementation of VADER was used to compute sentiment scores. For each Text entry, the analyzer returned four values (positive, negative, neutral, compound). Only the compound score was retained because it summarizes overall sentiment in a single metric. In addition, the compound score was mapped into discrete sentiment categories (Negative, Neutral, Positive) using the standard VADER thresholds (≤ −0.05, between −0.05 and 0.05, ≥ 0.05).
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Descriptive statistics and assumptions checking.Descriptive statistics (means, standard deviations, quartiles, and ranges) were calculated for sentiment, upvotes, and text length. Histograms and kernel density plots were inspected to understand the skewness of Upvotes and comment length. Although Upvotes were highly right-skewed, the extremely large sample size made parametric tests robust to non-normality, so no transformation was applied.
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Correlation analysis.Pearson correlation coefficients were computed among compound sentiment, Upvotes, word_length, and char_length. A correlation matrix and corresponding heatmap were created to visually inspect multicollinearity and to answer RQ3. Very high correlations between word_length and char_length were expected and confirmed.
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Pre–post comparisons.For RQ1 and RQ2, independent-samples t-tests compared mean sentiment and mean Upvotes between the Before and After periods. Effect sizes were summarized using Cohen’s d to distinguish statistically significant but practically small differences from more substantive shifts.
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Visualization.Several visualizations were planned and generated, including:
- Boxplots showing sentiment distributions before and after the launch
- Histograms and density plots of Upvotes and comment length
- Bar charts for Negative/Neutral/Positive sentiment proportions
- A correlation heatmap for all numeric variables
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Exploratory transformer pipeline.An Unsloth/transformer-based pipeline was partially configured in a GPU environment to fine-tune a sentiment classifier on a labeled subset of comments. However, due to GPU and library compatibility limitations, full fine-tuning and evaluation could not be completed. Therefore, RQ4 is addressed primarily in the Discussion as a conceptual extension rather than a fully executed model comparison.
3. Results
3.1. Descriptive Statistics
| compound | Upvotes | Word_length | Char_length | |
| count | 297533 | 297533 | 297533 | 297533 |
| mean | 0.132 | 5.199 | 48.880 | 290.216 |
| std | 0.470 | 48.901 | 128.699 | 871.489 |
| min | -1 | -249.00 | 1 | 4 |
| 25% | -0.0098 | 1 | 9 | 47 |
| 50% | 0 | 2 | 18 | 95 |
| 75% | 0.493 | 5 | 41 | 226 |
| max | 0.999 | 14165.0 | 2000 | 13920 |
3.2. Correlation Analysis (RQ3)

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Sentiment and engagement are nearly independent.The correlation between VADER compound sentiment and Upvotes was extremely small (r ≈ 0.00). This suggests that highly upvoted comments were not systematically more positive or negative than typical comments. Instead, upvotes likely reflect a mix of factors such as humor, perceived insight, or alignment with community norms.
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Sentiment and text length are modestly related.Compound sentiment showed small–to–moderate positive correlations with both word_length (r ≈ 0.25) and char_length (r ≈ 0.23). Longer comments tended to be slightly more emotional—either more strongly supportive or more strongly critical—than very short comments. This pattern supports the expectation that users expend more effort when they feel strongly about a topic.
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Text length measures are highly redundant.As expected, word_length and char_length were almost perfectly correlated (r ≈ 0.98). This indicates that either measure could be used as a proxy for comment size without major loss of information, and that multicollinearity is only a concern if both are entered into the same regression model.
3.3. Sentiment Change Before vs. After Launch (RQ1)

3.4. Engagement Differences (RQ2)

3.5. VADER Sentiment Categories
- Positive (compound ≥ 0.05): 41% of comments
- Neutral (−0.05 < compound < 0.05): 38% of comments
- Negative (compound ≤ −0.05): 21% of comments

3.6. Text Length Distributions


3.7. Exploratory Transformer Comparison (RQ4)
- Sampling a few thousand comments and manually labeling them as positive, neutral, or negative.
- Converting this labeled subset into a HuggingFace datasets object.
- Fine-tuning a small transformer model using Unsloth’s efficient training utilities.
- Comparing transformer predictions with VADER labels on a hold-out set.
4. Discussion
4.1. Summary of Findings
4.2. Limitations
4.3. Future Directions
4.4. Practical Implications
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| compound | upvotes | Word_length | Char_length | |
| compound | 1.00 | 0.002 | 0.252 | 0.231 |
| upvotes | 0.002 | 1.00 | 0.004 | 0.003 |
| Word_length | 0.252 | 0.004 | 1.00 | 0.982 |
| Char_length | 0.231 | 0.003 | 0.982 | 1.00 |
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