Inferential Stats

AQA psychology statistical tests

Sign Test

* difference
* related design
* nominal
* (SPACE)

Wilcoxon

* difference
* related design
* ordinal
* (WEATHER)

Related T-Test

* difference
* related design
* interval/ratio
* DF= n-1
* (REALLY)

Chi- Squared

* difference/association
* unrelated
* nominal
* (CONTAINS)

Mann-Witney

* difference
* unrelated
* ordinal
* (MANY)

Unrelated T-Test

* difference
* unrelated
* interval
* DF= (x+y)-2
* (UFOS)

Chi-Squared

* difference
* unrelated design
* nominal
* (CHASING)

Spearman’s Rho/Rank

* correlation
* ordinal
* DF= n-2
* (SMALL)

Pearson’s R

* correlation
* interval
* DF= n-2
* (PIGS)

if the test has an r in its name….

the calculated value must be equal or above the critical

type 1 errors

false positive test, often using a significance level that is too lenient and rejecting the null hypothesis when there is a possibility that the results are due to chance

type 2 errors

false negative result, often using a significance level that is too strict and accepting the null hypothesis when there is a possibility that the results were significant

what is a parametric test?

a test is based on population parameters and assumes. that there is normal distribution

what is a non-parametric test?

a test that doesn’t assume that the data is normally distributed or homogeneity