Core concepts
- 01Mean: arithmetic average; sensitive to extremes.
- 02Median: middle value of ordered data; robust to outliers.
- 03Mode: most frequent value.
- 04Dispersion measures: range, mean deviation, standard deviation, variance.
- 05Empirical relation: Mode = 3 Median − 2 Mean (for moderately skewed).
Flowchart summary
Central Tendency | +-- Mean (AM, GM, HM) +-- Median +-- Mode Dispersion | +-- Range +-- MD +-- SD / Variance +-- CV (relative)
Exam-critical pointers
- ⭐AM ≥ GM ≥ HM for positive numbers (equality when all equal).
- ⭐SD unaffected by change of origin, affected by change of scale.
- ⭐For symmetrical distribution: Mean = Median = Mode.
- ⭐CV used to compare variability of two datasets with different units.
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