Measures of Central Tendency

The three classic summaries — mean, median, and mode — answer different questions. The mean is the arithmetic average; the median is the middle of the sorted data; the mode is the most frequent value. Comparing them reveals skew: mean above median signals a right-skewed distribution (a few large outliers).

Measures of Spread

Range (max − min), variance, and standard deviation quantify spread. The sample standard deviation (n−1 denominator) estimates population variability from a sample and is the default for real-world data analysis. Quartiles and the interquartile range offer outlier-robust alternatives.

Reading the Output

Use mean and median together for center, std deviation for spread, and the chart to spot outliers visually. With roughly bell-shaped data, about 68% of values fall within one standard deviation of the mean — a fast sanity check on your data.