Percent of numbers that are less than a number plus half of percent of numbers equal to the number is a statistic {percentile rank} {percentile}|. For example, if n is at 50th percentile {second quartile, percentile} {fifth decile}, half of all values are less than or equal to n.
Dispersion {inter-quartile range} can be between lower quartile 25% and upper quartile 75%. Median splits inter-quartile range.
Value has cumulative probability {quantile} {inverse density function} {percent point function} for that value and all lower values. Quantile function is integral of probability function from minimum to value.
For distributions, one quarter {quartile} goes from 0th to 25th percentile {first quartile}. One quarter goes from 25th to 50th percentile {second quartile, distribution}. One quarter goes from 50th to 75th percentile {third quartile}.
Deviation {quartile deviation} (Q) can be half the difference between first and third quartiles.
3-Statistics-Statistical Population
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Date Modified: 2022.0225