Difference between third and first quartiles.
InterquartileRange[data]
InterquartileRange[data, {{a, b}, {c, d}}]
InterquartileRange[dist]
InterquartileRange[{1, 3, 5, 7, 9}]
→ 5InterquartileRange[{{1, 10}, {2, 20}, {3, 30}, {4, 40}}]
→ {2, 20}InterquartileRange[{1, 2, 3, 4, 5, 6, 7, 8}, {{0, 0}, {1, 0}}]
→ 4