AP Statistics Unit 1

Quantitative variable

something that can be measured

quantitative variables: discrete

measured by whole numbers and cannot be fractioned.

quantitative variable: continuous

measured by fractions or decimals, e.g. weight or height

quantitative variable: parameter

a number describing the whole population

quantitative variable: statistic

a number that represents a sample

variance

calculate the mean, find each number's difference from that mean, square each difference, add those squared values together, and divide the total by the count of values (n) for a population or (n - 1) for a sample.

outlier formula

upper: Q3 + 1.5(IQR)

lower: Q1 - 1.5(IQR)

center

Could be mean or median. Mean if there are no outliers, median if there are.

variability

how spread out the data is. If there are outliers in the dataset, we do not use standard deviation to measure variability; we instead use IQR.

Z-score

(individual value - mean) / standard deviation