9.3 Confidence Intervals and the t-Distribution

ȳ = t_n-1 * SE(ȳ)

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

n-1

the number of degrees of freedom

randomization condition

the data is drawn from a random sample - one of the conditions that must be true to use the student’s t

10% condition

the sample size is less than 10% of the population - one of the conditions that must be true to use the student’s t

degrees of freedom

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

SE(ȳ) = s / (√n)

the formula for the standard error of the mean

nearly normal condition

the data comes from a distribution that is unimodal and symmetrical, without skewness or outliers - one of the conditions that must be true to use the student’s t

independence assumption

the participants in a sample are independent of one another - one of the conditions that must be true to use the student’s t