Significance tests Flashcards
What is a null hypothesis?
A null hypothesis (H0) states that two treatments are equally effective
What is a significance test used for?
uses the sample data to assess how likely the null hypothesis is to be correct.
What is an alternative hypothesis?
alternative hypothesis (H1) is the opposite of the null hypothesis, i.e. There is a difference between the two treatments
What is the p value
probability of obtaining a result by chance at least as extreme as the one that was actually observed, assuming that the null hypothesis is true
What is meant by the “power of a study”
the probability of (correctly) rejecting the null hypothesis when it is false, i.e. the probability of detecting a statistically significant difference
Significance tests used if the data is parametric
Student’s t-test - paired or unpaired*
Pearson’s product-moment coefficient - correlation
What significance tests can be used if data is non-parametric
Mann-Whitney U test
- compares ordinal, interval, or ratio scales of unpaired data
Wilcoxon signed-rank test
chi-squared test
Spearman, Kendall rank - correlation
This test compares two sets of observations on a single sample, e.g. a ‘before’ and ‘after’ test on the same population following an intervention
Wilcoxon signed-rank test
This test is used to compare proportions or percentages e.g. compares the percentage of patients who improved following two different interventions
chi-squared test
