Psychology I / Descriptive Statistics
Practice question · Sort into groups

You add one extreme outlier to a data set. Sort each statistic by how much that single outlier moves it.

Groups: Strongly affected by the outlier · Barely affected by the outlier

Hints
  1. Ask which statistics use every value's exact size (or the extremes) versus only position or frequency.
  2. Mean, range, and SD all feed on the actual magnitudes; median and mode depend on position and frequency.
Show the answer

Strongly affected by the outlier: The mean, The range, The standard deviation

Barely affected by the outlier: The median, The mode

Why

The mean, range, and standard deviation all incorporate the outlier's raw magnitude, so they shift strongly; the median (a position) and mode (a frequency) barely move. This robustness split is the whole reason we ever prefer the median.

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