Understanding QQ Plot for Normal Distribution

Day 37 - QQ Plot Hey Network, Our today topic is about the QQ plot so let's discuss it. Have you ever asked yourself while working with your project that "Is my data normally distributed?" This is the most asked question before running any ML model. And most people answered it wrong. The right tool? A QQ Plot. Here's exactly how to read one. QQ stands for Quantile - Quantile. The Idea is simple: → Short your data → get its quantiles(1st, 2nd, 3rd....100th percentile) → Compare those quantile to what a perfect normal distribution would have. → Plot them against each other If your data is normal: All points fall on a straight diagonal line. Perfect alignment. If your data is not normal, you see patterns: S-curve bending upward at both ends → leptokurtic (fat tails) S-curve bending inward → platykurtic (thin tails) Points curve up at the right end → right skew Points curve down at the left end → left skew points along diagonal except at extremes → outliers only We have 3 ways to test normality: 1. Visual inspection ( histogram / KDE) → quick but subjective 2. QQ Plot → visual + pattern - based → my favourite 3. Statistics tests (Shapiro - Wilk, Kolmogorov - Smirnov) → gives p-value < 0.05 = not normal And no, QQ plot aren't only for normal distributions. You can compare your data to ANY reference distribution: uniform, exponential, Pareto. In python: Import statsmodels.api as sm sm.qqplot(data, line='45') Straight line = you're good to go. Banana curve = rethink your assumptions. #Statistics #DataScience #DataAnalyst #EDA #FraudAnalyst #PublicLearning

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