OLS NBR ITS

analysis/analysis5.ipynb

@@ -1,5 +1,37 @@
 {
  "cells": [
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Colorado Spills Project\n",
+    "## Outline\n",
+    "\n",
+    "1. **Data Import and Preparation**\n",
+    "    - Import necessary libraries and load data from the database.\n",
+    "    - Convert data into GeoDataFrame and ensure proper formatting.\n",
+    "\n",
+    "2. **Data Cleaning**\n",
+    "    - Handle missing or incorrect data.\n",
+    "    - Filter out data for the year 2024.\n",
+    "\n",
+    "3. **Exploratory Data Analysis**\n",
+    "    - Separate historical and recent spills.\n",
+    "    - Analyze reporting delays and trends over time.\n",
+    "\n",
+    "4. **Visualization**\n",
+    "    - Create spatial distribution maps.\n",
+    "    - Plot trends and differences in reporting delays.\n",
+    "\n",
+    "5. **Statistical Analysis**\n",
+    "    - Perform t-tests to compare response times.\n",
+    "    - Use regression models to analyze differences and trends.\n",
+    "\n",
+    "6. **Results and Interpretation**\n",
+    "    - Summarize findings in markdown cells.\n",
+    "    - Highlight key takeaways and policy implications.\n"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 3,
@@ -1413,9 +1445,17 @@
     "\n",
     "The fixed-effects model confirmed our core finding: **recent spills diverged significantly from historical trends in key policy-relevant years**. In 2020, historical spills experienced a 33-day increase in reporting delay, while recent spills showed a 33-day smaller delay—resulting in a significant 66-day relative difference (p = 0.006). Significant differences were also observed in 2015 and 2019, further reinforcing the conclusion that recent spills were less affected by structural or reporting challenges.\n",
     "\n",
-    "### **Summary**\n",
+    "### **Reasons DiD Model Is Inappropriate**\n",
     "\n",
-    "Across all models, results consistently show that **the 2021 policy change was associated with improved reporting timeliness**, particularly for historical spills. While recent spills already had shorter delays and showed smaller improvements, the fixed-effects model demonstrated that these trends were distinct and consistent with industry adaptation and improved detection technologies. Together, the findings suggest that the policy change not only reduced delays but also helped standardize reporting practices across different types of spills."
+    "A difference-in-differences (DiD) design assumes parallel pre-policy trends between treated and control groups. In our case, *historical* and *recent* spills are fundamentally different: recent spills are reported shortly after discovery, while historical spills reflect delayed discoveries. Because their reporting dynamics are structurally distinct and not plausibly parallel over time, DiD is not an appropriate design.\n",
+    "\n",
+    "### **Key Takeaways**\n",
+    "- **Historical spills**: Showed significant improvement in reporting delays post-2020, with a 16.2-day reduction.\n",
+    "- **Recent spills**: Experienced a smaller, marginally significant reduction of 1.8 days.\n",
+    "- **DiD model**: Indicated that historical spills improved significantly more than recent spills, but the parallel trends assumption is violated.\n",
+    "- **Fixed-effects model**: Confirmed that recent spills diverged from historical trends, particularly in key years (2015, 2019, 2020), reinforcing the idea that recent spills are less affected by structural challenges.\n",
+    "- **Policy implications**: The 2021 policy change appears to have standardized reporting practices and improved timeliness, particularly for historical spills, suggesting that regulatory changes can effectively address reporting delays.\n",
+    "\n"
    ]
   }
  ],