Choosing a statistical test

Inferential statistics?

statistics used to help us judge whether our results are statistically significant or are due to chance

1st question?

Is the study testing a difference or a correlation? ​

Is the study testing a difference or a correlation? - tip 1: graphs?

scattergrams are used for correlations​ - All other graphs are used for differences ​

Is the study testing a difference or a correlation? - tip 2: what will it always tell you in the stem?

whether the study is testing a difference or correlation (or “relationship”) ​

Testing for a difference?

when you are trying to establish a difference between two groups using an experiment

Testing for a correlation?

when you are trying to establish a correlation between two covariables using a correlational study

2nd question - when does it only apply?

when testing a difference

2nd question?

Was the experimental design related or unrelated?​

Was the experimental design related or unrelated?​ - related designs (2)?

repeated measures (same participants in both conditions) and matched pairs (different participants in both conditions)

Was the experimental design related or unrelated?​ - unrelated design?

independent groups (completely different participants in both conditions)

3rd question?

Is the data nominal, ordinal or interval?​

Choosing a statistical test table?

…

How to remember the table?

Carrots, Should, Come, Mashed, With, Swede, Under, Roast, Potatoes

Chi-Squared test?

an inferential statistic used when testing for a difference or correlation, using a unrelated design and nominal data

Sign test?

an inferential statistic used when testing for a difference, using a related design and nominal data

Mann-Whitney U?

an inferential statistic used when testing for a difference, using an unrelated design and ordinal data

Wilcoxon?

an inferential statistic used when testing for a correlation, with at least one covariable measured on an ordinal scale

Spearman’s Rho?

an inferential statistic used when testing for a correlation with at least one covariable measured on an ordinal scale

Unrelated t-test?

an inferential statistic used when testing for a difference, using an unrelated design and interval data

Related t-test?

an inferential statistic used when testing for a difference, using a related design and interval data

Pearson’s R?

an inferential statistic used when testing for a correlation, with both covariables measured on an interval scale