Analyzing Data

Analyzing Data

Overview

A protocol for Python-based data analysis that prevents hallucination by requiring explicit column understanding, separating metrics from implications, and labeling all hypotheses.

When to Use

• User provides CSV, Excel, or structured data files
• User asks for "analysis", "insights", "metrics", "trends", or "charts"
• Data exists in data/ or inputs/ folder
• User wants to understand product performance

Core Pattern

Step 1: Exploratory Data Analysis (EDA)

Write and execute a Python script to produce:

import pandas as pd

# Load data
df = pd.read_csv('inputs/data/filename.csv')  # or pd.read_excel()

# Basic info
print("=== SHAPE ===")
print(df.shape)

print("\n=== COLUMNS & TYPES ===")
print(df.dtypes)

print("\n=== FIRST 5 ROWS ===")
print(df.head())

print("\n=== SUMMARY STATS ===")
print(df.describe(include='all'))

print("\n=== MISSING DATA ===")
print(df.isnull().sum() / len(df) * 100)

Step 2: Data Dictionary

Create a data dictionary table:

Rules:

• Mark meaning as "Unknown" if not explicitly documented
• Do NOT infer column meanings from names alone
• Ask user to clarify unknown columns before proceeding

Step 3: Analysis Plan

Only propose analyses where:

• Required columns have known meanings
• User has confirmed the business context
• The analysis directly answers user's question

Step 4: Execution & Visualization

import matplotlib.pyplot as plt

# Example: Time series
df['date'] = pd.to_datetime(df['date_column'])
daily = df.groupby('date').size()
daily.plot(figsize=(10,5), title='Daily Counts')
plt.savefig('outputs/insights/analysis_output.png')
print("Chart saved to outputs/insights/analysis_output.png")

Step 5: Generate Output

Write to outputs/insights/data-analysis-YYYY-MM-DD.md:

---
generated: YYYY-MM-DD HH:MM
skill: analyzing-data
sources:
  - inputs/data/filename.csv (modified: YYYY-MM-DD)
downstream: []
---

# Data Analysis: [Dataset Name]

## Dataset Overview
| Attribute | Value |
|-----------|-------|
| Rows | N |
| Columns | N |
| Date range | [if applicable] |

## Data Dictionary
| Column | Type | Example Values | Meaning |
|--------|------|----------------|---------|
| ... | ... | ... | Explicit/Unknown |

## Key Metrics
| Metric | Value | Source |
|--------|-------|--------|
| [Metric name] | [Number] | [Code output] |

## Findings
1. **[Finding]** — Evidence: [code output]

## Hypotheses (require validation)
1. **[Hypothesis]** — Based on: [observation]

## Visualizations
- [Chart description]: outputs/insights/[filename].png

## Sources Used
- [file paths]

## Claims Ledger
| Claim | Type | Source |
|-------|------|--------|
| [Metric] | Evidence | [Python output] |
| [Trend interpretation] | Hypothesis | [Based on metric X] |

Step 6: Copy to History & Update Tracker

• Copy to history/analyzing-data/data-analysis-YYYY-MM-DD.md
• Update alerts/stale-outputs.md

Quick Reference

Common Mistakes

• Assuming column meanings: "user_id probably means..." → Ask user to confirm
• Stating implications as facts: "Users are churning because..." → Label as hypothesis
• Using sample data for conclusions: "Based on 10 rows..." → Ensure representative data
• Ignoring missing data: 50% nulls in key column → Report this prominently
• No data dictionary: Jumping to analysis → Always document columns first

Verification Checklist

• Data dictionary created with all columns
• Unknown meanings explicitly marked
• User confirmed column semantics before analysis
• Metrics separated from hypotheses
• Missing data reported
• Charts saved to outputs/insights/
• All code executed successfully
• Metadata header complete
• Copied to history, tracker updated

Evidence Tracking