quartiles
-th, the second quartile (which is the median) Q2 is the 
-th, and the third quartile (or upper quartile) Q3 is the 
-th in ascending order. When 
is not a whole number, it is sometimes thought necessary to take the (weighted) average of two observations, as is done for the median. However, unless n is very small, an observation that is nearest will normally suffice. For example, for the sample 15, 37, 43, 47, 54, 55, 57, 64, 76, 98, we may take Q1=43, Q2=54.5, and Q3=64.
For a random variable, the quartiles are the quantiles x0.25, x0.5, and x0.75; that is, the 25th, 50th, and 75th percentiles.
- harmonic sequence
- harmonic series
- hash function
- Hausdorff dimension
- Hausdorff, Felix
- Hausdorff space
- Hawking, Stephen William
- Hawthorne effect
- hcf
- heat
- heat equation
- Heaviside function
- hectare
- hecto‐
- height
- Heine-Borel theorem
- Heisenberg's uncertainty principle
- Heisenberg, Werner Karl
- helicoid
- helix
- hemisphere
- hemi‐
- hendecagon
- heptagon
- hepta‐