Types of test Flashcards
How are 2 independent groups typically compared
- Randomised study (invention vs control)
- Cohort studies (exposed v non exposed)
What is assumed when doing an unpaired t-test?
- Variable is normally distributed
- Standard deviation is similar in two groups
- participants are independent between groups
Which hypothesis is tested in an unpaired t-test?
That there is no difference between the two groups (null) (the most boring one)
Interpretation of P value
P < 0.001 (strong evidence against null hypothesis)
P < 0.05 (moderate)
P > 0.1 (little)
P = 1 (none)
What is a paired test design?
Participants are paired up (eg age, gender) then put in separate groups so the groups are separate but paired
Measurements are taken before and after intervention and then compared
What is analysis variance?
ANOVA test
a method for hypothesis testing - proves a global p-value comparing been across all groups
What is assumed when hypothesis test mean across 3 or more independent groups
- Similar SD
- Independent participants
- Normally distributed / non skewed variable
when data is paired how does analysis of variance vary?
it is repeated
Assumptions when comparing mean across 3 or more paired groups?
difference scores normally distributed or not too skewed
SD of differences scores should be similar for any combination of groups
when is a post hoc pairwise comparison used?
when p is < 0.05 and you want to compare groups to each other
when using non-parametric methods how should groups be summarised?
using medians & interquartile ranges
when should non-parametric methods be used?
when the assumptions for parametric methods are not met
what test is used when comparing a quantitative variable between two independent groups?
Mann Whitney test
what test is used when comparing a quantitative variable between 3 or more independent groups?
Kruskal-Wallis test
what test is used when comparing a quantitative variable between 2 paired groups?
Wilcoxon signed ranks test
