Median

The exam rarely asks you to just compute a median; the harder version hands you a skewed data set (incomes, returns, drawdowns) and asks which measure of central tendency is most appropriate, where the answer hinges on median because outliers distort the mean. Watch for the positional tell: the median sits at the (n + 1)/2-th position of the ordered observations, so a vignette handing you that location index is steering you toward it. The median is also the 50th percentile (second quartile, Q2), the center of the five-number summary, so quartile and percentile items quietly test the same skill.

The classic trap is reaching for the mean out of habit on tail-heavy data, or misreading the skew direction: positive skew pulls the mean above the median (the examTip rule), so a long right tail gives mean > median > mode. Another snare is forgetting to sort first before picking the middle value. Memory hook: the median is the “middle child” — it ignores how loud the extremes shout and just holds the center position.