How do you read a Q-Q plot?

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Answer

$Q-Q (quantile-quantile) plot: plot empirical quantiles vs theoretical quantiles (typically normal).$
$Perfect fit \to points on the y=x line.$
$Deviations reveal distribution shape: (1) S-shape \to heavier or lighter tails than normal; (2) curved \to skew; (3) points off at the ends \to outliers.$
$Fast visual check for normality / distributional fit before running parametric tests.$
$Complement with Shapiro-Wilk / Kolmogorov-Smirnov for formal tests.$

Check yourself — multiple choice

Same as histogram
Empirical quantiles vs theoretical; on-line → fit; S/curve → tails/skew; ends deviate → outliers
Only for classification
Requires bins

Q-Q plot: empirical vs theoretical quantiles; deviations reveal shape.

#descriptive#eda

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