Significant Test Type Flashcards
What are the parametric (something which can be measured, usually normally distributed)
Student’s t-test - paired or unpaired
Pearson’s product-moment coefficient - correlation
What are the non parametric test
Mann-Whitney U test
Wilcoxon signed-rank test
chi-squared test
Spearman, Kendall rank - correlation
What is Mann Whitney U test
compares ordinal, interval, or ratio scales of unpaired data (Unpaired data comes from two different groups of patients, e.g. Comparing response to different interventions in two groups)
What is chi squared test ?
Paired data (obtained from a single group of patients)
used to compare proportions or percentages e.g. compares the percentage of patients who improved following two different interventions
What is Wilcoxon signed-rank test?
compares two sets of observations on a single sample, e.g. a ‘before’ and ‘after’ test on the same population following an intervention
Paired
Spearman, Kendall rank ?
Correlation
Two types of errors may occur when testing the null hypothesis
type I: the null hypothesis is rejected when it is true - i.e. Showing a difference between two groups when it doesn’t exist
type II: the null hypothesis is accepted when it is false -
The power of a study is
probability of detecting a statistically significant difference (probability that a statistically significant difference will be detected)
the probability of (correctly) rejecting the null hypothesis when it is false
power can be increased by
increasing the sample size
power =
1 - the probability of a type II erro
NNT
1/ absolute risk reduction
Properties of the Normal distribution- values lie within 1 SD of the mean
68.3%
Properties of the Normal distribution - values lie within 1 SD of the mean
68.3%
Properties of the Normal distribution - values lie within 2 SD of the mean
95.4%
Properties of the Normal distribution - values lie within 3 SD of the mean
99.7%
