Introduction to Probability Definitions (Ch. 1)

Population

the complete collection of subjects on which we wish to infer

Population parameters

a numerical summary concerning the complete collection of subjects, noted by μ

Sample

a (random) subset of the population

Sample statistic

a numeral summary concerning a subset of the population, noted with “hat” symbol

Mean

the arithmetic average of the observations
x̄ = 1/n _i=1∑ⁿ x_i

p^th percentile value

divides the ordered data such that p% of the data are less than that value and (100-p)% greater than it
the median is the 50th percentile

Mode

the most frequently encountered observation

α% trimmed mean

the mean of the data with the smallest α% * n observations and the largest α% * n observations truncated from the data
50% = median, trimmed 50% from each side