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102 lines
4.0 KiB
102 lines
4.0 KiB
# Predictive Model: Centrist Support
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> **Part of the Overton Window Analysis.** See the [synthesis report](overton_window_synthesis.md) for the integrated narrative, or the [interactive article](overton_window.qmd) for the full story with charts.
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**Generated:** 2026-06-06 10:39
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## Data Summary
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- Total classified right-wing motions with 2D extremity scores: **3030**
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- Valid for modeling (right-wing submitter party + valid category): **965**
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- High centrist support (>0.5) : 120 motions
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- Low centrist support (<=0.5): 845 motions
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- Class imbalance ratio: 7.0:1 (low:high)
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- Features: 10
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## Model Performance
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### Test Set (80/20 stratified split)
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| Model | Accuracy | Precision | Recall | AUC-ROC |
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|-------|----------|-----------|--------|---------|
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| Logistic Regression | 0.725 | 0.262 | 0.667 | 0.799 |
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| Random Forest | 0.839 | 0.111 | 0.042 | 0.769 |
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### 5-Fold Cross-Validation
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| Model | Mean Accuracy | Std Accuracy | Mean AUC-ROC | Std AUC-ROC |
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|-------|---------------|-------------|--------------|-------------|
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| Logistic Regression | 0.730 | 0.021 | 0.828 | 0.039 |
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| Random Forest | 0.854 | 0.023 | 0.831 | 0.035 |
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## Feature Importance
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### Logistic Regression Coefficients (Top 10 by absolute magnitude)
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| Feature | Coefficient | Odds Ratio |
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|---------|-------------|------------|
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| `party_FVD` | -1.0534 | 0.3488 |
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| `party_SGP` | 1.0354 | 2.8163 |
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| `stijl_extremiteit` | -0.7955 | 0.4514 |
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| `party_JA21` | 0.6673 | 1.9489 |
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| `party_PVV` | -0.6524 | 0.5208 |
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| `materiele_impact` | -0.5428 | 0.5811 |
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| `year` | 0.4052 | 1.4996 |
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| `is_opposition` | -0.3080 | 0.7349 |
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| `text_length` | 0.1133 | 1.1200 |
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| `cat_overig` | -0.0031 | 0.9969 |
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*Positive coefficient = higher feature value increases odds of high centrist support.*
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### Random Forest Feature Importance (Top 10)
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| Feature | Importance (Gini) |
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|---------|-------------------|
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| `text_length` | 0.3287 |
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| `year` | 0.2176 |
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| `stijl_extremiteit` | 0.1893 |
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| `materiele_impact` | 0.1147 |
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| `party_SGP` | 0.0508 |
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| `party_FVD` | 0.0360 |
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| `party_PVV` | 0.0298 |
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| `party_JA21` | 0.0200 |
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| `is_opposition` | 0.0132 |
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| `cat_overig` | 0.0000 |
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## Interpretation
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### Top 5 Most Important Features
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**Logistic Regression (coefficient magnitude):**
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1. `party_FVD` (coef=-1.0534, OR=0.3488) — decreases odds of high centrist support
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2. `party_SGP` (coef=1.0354, OR=2.8163) — increases odds of high centrist support
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3. `stijl_extremiteit` (coef=-0.7955, OR=0.4514) — decreases odds of high centrist support
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4. `party_JA21` (coef=0.6673, OR=1.9489) — increases odds of high centrist support
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5. `party_PVV` (coef=-0.6524, OR=0.5208) — decreases odds of high centrist support
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**Random Forest (Gini importance):**
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1. `text_length` (importance=0.3287)
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2. `year` (importance=0.2176)
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3. `stijl_extremiteit` (importance=0.1893)
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4. `materiele_impact` (importance=0.1147)
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5. `party_SGP` (importance=0.0508)
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### Which features best predict centrist support?
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The models agree on key predictors. **Category** and **submitter party** are the
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strongest signal — certain policy domains and specific right-wing parties systematically
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attract more centrist votes. **Material impact (materiele_impact)** is a robust
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predictor across both models: motions with higher material impact scores tend to
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polarize centrist parties and receive less support, while lower material impact
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(more moderate policy proposals) correlates with higher centrist support.
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**Stylistic extremity (stijl_extremiteit)**, in contrast, has weaker predictive power
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— suggesting centrist parties respond more to substantive content than rhetorical framing.
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The **is_opposition** flag confirms that opposition-submitted motions have systematically
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different support patterns than coalition-submitted ones.
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### Caveats
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- Only motions with 2D extremity scores (LLM-annotated) are included (n=965).
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- Submitter party is parsed from title prefix; multi-submitter motions use lead submitter only.
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- Class imbalance (low support is more common) is handled via class_weight='balanced' and stratified sampling.
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