Statistical testing Flashcards
What is the purpose of statistical testing?
- To determine whether a significant difference or correlation exists, and whether the null hypothesis should be accepted or rejected
What are the 3 factors that should be considered when deciding which test to use?
1) Difference (/correlation)
2) Design
3) Data
What are the 3 levels of measurement?
1) Nominal (category data- shows preference)
2) Ordinal (ordered with an uneven scale- ratings)
3) Interval (ordered with standardised scale)
What are parametric tests and when are they used?
- Powerful and robust tests- able to detect significance
- Used when: data is interval, population has a normal distribution, homogenity of variance (similar standard deviation)
What are non-parametric tests and when are they used?
- Less powerful- used when parametric conditions are not used
- Used when: data is nominal/ ordinal, population has a skewed distribution
What test would I use if…?
- difference
- nominal
- unrelated
Chi-squared
What test would I use if…?
- difference
- nominal
- related
Sign test
What test would I use if…?
- difference
- ordinal
- unrelated
- Mann-Whitney U
What test would I use if…?
- difference
- ordinal
- related
- Wilcoxon
What test would I use if…?
- difference
- interval
- unrelated
- Unrelated t-test
What test would I use if…?
- difference
- interval
- related
- Related t-test
What test would I use if…?
- correlation
- nominal
- Chi-squared
What test would I use if…?
- correlation
- interval
- Pearson’s r
What test would I use if…?
- correlation
- ordinal
- Spearman’s rho
What are type 1 errors?
- Null hypothesis has been rejected
- But null hypothesis is TRUE
- False positive
