statistical tests

Question 1

difference or association

Answer 1

• data investigating a difference will usually have 2 conditions, a control and an experimental. this is usually a typical experiment
• or a psychologist may be establishing an association/ relationship between 2 co-variables. this is usually a correlational study

Question 2

experimental design

Answer 2

• should only consider this when looking for a difference
• related data refers to when participants in each condition are somehow related: repeated measures or matched pairs
• unrelated data refers to having 2 separate groups of people in each condition: independent groups

Question 3

nominal data

Answer 3

• categorical data
• the data is discrete, it will only appear in one category
• e.g. if a researcher wanted to know if more students doing psych went to a school or college, the data would be categorised as ‘school’ or ‘college’

Question 4

ordinal data

Answer 4

• data which is ordered somehow and the intervals between data aren’t equal
• ranking data where values assigned have no meaning besides stating where one scores in relation to another
• e.g. someone ranking their preference of local restaurants from 1 to 10. the difference between 1st and 2nd will probably be different to the difference between 8th and 9th

Question 5

interval data

Answer 5

• data which is ordered somehow
• the intervals between each value are equal in measurement
• e.g. time, temperature

Question 6

acronym for the order of tests

Answer 6

simon - sign test
cowell - chi-squared
wants - wilcoxon
more - mann whitney
singers - spearman’s rho
receiving - related t-test
unanimous - unrelated t-test
praise - pearson’s r

Question 7

parametric and non-parametric tests

Answer 7

-parametric tests are preferred as they’re more powerful, but they require certain criteria:
- data should be interval
- data should be drawn from an underlying normal distribution
- should be homogeneity of variance (the variances in the two groups shouldn’t be significantly different)
- the 3 parametric tests required are the related t-test, the unrelated t-test and pearson’s r