Stats Terms

Null Hypothesis

a hypothesis that there is no significant difference between specified populations

Null Distribution

the distribution of two sets of data under a null hypothesis

p-value

probability of a specific statistical measure

test statistic

describes how far your observed data is from the null hypothesis

critical values

the value of the test statistic which defines the upper and lower bounds of a confidence interval, or which defines the threshold of statistical significance in a statistical test

confidence intervals

the probability that a population parameter will fall between a set of values for a certain proportion of times

one sided vs two sided test

A one-tailed test looks for an “increase” or “decrease” in the parameter whereas a two-tailed test looks for a “change” (could be increase or decrease) in the parameter

significance level

statistical significance is determined by citing an alpha level, or the probability of rejecting the null hypothesis when the null hypothesis is true

type 1 vs type 2

A type I error (false-positive) occurs if an investigator rejects a null hypothesis that is actually true in the population; a type II error (false-negative) occurs if the investigator fails to reject a null hypothesis that is actually false in the population

standard deviation

a measure of how dispersed the data is in relation to the mean