Half the interquartile range of a list under optional Quantile parameters (or columnwise for a matrix)
QuartileDeviation[data]
QuartileDeviation[data, {{a, b}, {c, d}}]
QuartileDeviation[dist]
QuartileDeviation[{1, 3, 4, 2, 5, 6}]
→ 3/2QuartileDeviation[ExponentialDistribution[λ]]
→ (Log[4]/λ - Log[4/3]/λ)/2QuartileDeviation[{1, 3, 2, 7}]
→ 7/4