research methods: Choosing a statistical test Flashcards
1
Q
What should we consider when choosing a stat test?
A
- Are we looking for a difference or a correlation?
- What experimental design was used?
- What level of measurement was used?
2
Q
What does a difference vs correlation refer to?
A
- Relates to the aim or purpose of the investigation
- Will be evident in the wording of the hypothesis
3
Q
What experimental designs are there and what data do they produce?
A
- Independent groups -> unrelated
- Repeated measures -> related
- Matched pairs -> related
4
Q
What levels of measurement are there?
A
- Nominal data
- Ordinal data
- Interval data
5
Q
What is nominal data?
A
- Data that is represented in the form of categories
- Is discrete because one item can only appear in one category
6
Q
What is ordinal data?
A
- Data that is ordered in some way
- Does not have equal intervals between each unit
- Lacks precision because it is based on subjective opinion rather than objective measurement
- Raw data is converted into ranks e.g. 1st, 2nd, 3rd and these ranks are used in the testing
7
Q
What is interval data?
A
- Data that is based on numerical scales that include units of equal, precisely defined size
- the most precise and sophisticated form of data in psychology
8
Q
What are the parametric tests?
A
- Related t-test
- Unrelated t-test
- Pearson’s R
9
Q
What are the advantageous features of parametric tests?
A
- Much more powerful and robust than other tests
- Use only the most trustworthy data
- Only use interval data
- If a psychologist can use a parametric test, they will, as these tests may be able to detect significance within some data sets that non-parametric tests cannot
10
Q
What are the three criteria of parametric tests?
A
- Data must be interval level because parametric tests use the actual scores rather than rank
- Data must be drawn from a population that would be expected to have a normal distribution
