273 Exam 3 pt. 1 [12, 14] - Z scores, probability, chi

Z scores, probabilities, chi square goodness of fit

probability

quantifies uncertainty, providing a measure between 0 (impossible event) and 1 (certain event)

normal

in a _______ distribution, mean = median = mode

Z scores

__________ transform data into a common scale: the standard normal distribution (mean = 0, SD = 1)

(reference value - mean)/SD

what is the formula for a z score?

the reference value is 1 standard deviation from the mean

a z-score of 1 means…

chi square goodness of fit

a _______ _______ test allows you to test whether a distribution of FREQUENCIES is different from what is EXPECTED

binomial

a ______ test is similar to a chi square goodness of fit test, but is only used if there are TWO levels of a category

degrees of freedom

_____ ___ _______ describes your “options” which are constrained based on what choice you have made/what you have left

sample size

what determines DOF?

critical

DOF determines the ______ value

difference, large

P- value: the probability of observing a _________, at least as ______ given that the null hypothesis is true.

fail to reject

if p>0.05, ____ the null hypothesis

reject

if p < 0.05, ____ the null hypothesis

chi square

example: I polled 1107 UNC undergraduate students. I want to know whether the distribution of their PA is different from the rest of the US — what test would you use?