Types of Data and Statistical Tests

Nominal data ------> The level of measurement where scores are placed in categories.

i.e. smokers and non-smokers, pink and not pink etc.

Ordinal data------> The level of measurement where scores are ranked/ordered but no measurements are made.

i.e. Heights- smallest to largest etc.

Interval data-------> The levels of measurement where scores are ranked but the "distance between one score and another is known.

This "distance" is known as an interval.

i.e. Exact height measurements

There are 4 statistical tests:

• Spearman's Rho
• Chi^2 (Chi square test)
• Wilcoxon Sign test
• Mann-Whitney test

Each test goes with a certain type of data and has a criteria which tells us when to use it.

Interval data:

• Spearman's Rho
• Mann Whitney test

Ordinal data:

• Spearman's Rho
• Wilcoxon Sign test
• Mann Whitney test

Nomial data:

• Chi square test

Use when:

• The hypothesis predicts an association between two variables

• The sets of data are independant

Use when:

• The hypothesis predicts a correlation between two variables

• The two sets of data are pairs of scores from one person/thing

• The data are ordinal or interval

Use when:

• The hypothesis predicts a difference between two sets of data

• The two sets of data are from seperate groups of participants

• The data are ordinal or interval

Use when:

• The hypothesis predicts a difference between two sets of data

• The two sets of data are pairs of scores from one person

• The data are ordinal or interval