Statistical tests

Question 1

Identifying the appropriate test

Answer 1

1. Correlation or difference?
2. How many groups? Dependent or independent?
3. Identify variables and data types
4. Establish if parametric vs non-parametric tests should be used
5. Select test

Question 2

Nominal

Answer 2

Observed values can be put into set categories which have no particular order or hierarchy

Question 3

Ordinal

Answer 3

Observed values can be put into categories which themselves can be ordered

Question 4

Interval

Answer 4

A measurement where the difference between values correspond to real differences between the quantities that the scale measures

Question 5

Ratio (continuous)

Answer 5

Like interval scales except they have true zero points (0 relates to the absence of something)

Question 6

Parametric tests

Answer 6

Should be used if:
1. Normal distribution, interval / ratio variables
2. Variability within each group should be approximately equal
3. Data points should be independent of each other (no pairing or repeated sampling)
4. Dependent variable must be interval or ratio