9.2 The t-Distribution

standard deviation

a value used to represent the amount of overall deviation or variation in a group

standard error

a number calculated from sample data that is used to estimate the standard deviation of a sampling distribution

n-1

the number of degrees of freedom

ȳ ± t_n-1 * SE(ȳ)

the formula for a one-sample t-interval for the mean

student’s t

a family of distributions organized by degrees of freedom - these distributions are unimodal and symmetrical, tending to have fatter tails and become more normal as the degrees of freedom increase

SE(ȳ) = s/√n

the formula for the standard error of the mean

degrees of freedom

the number of scores or values in a distribution that are free to vary