What test to do when? Flashcards
For a hypothesis test of the mean/ median, when do you approach using the normal distribution z-score?
Normally distributed
Comparing one-sample against a reference
Independent samples
Known population S.D.
Large sample size?
For a hypothesis test of the mean/ median, when do you use the one-sample T-test?
Normally distributed
Comparing one-sample against the reference
Independent samples
Population standard deviation unknown
Small sample size
For a hypothesis test of the mean/ median, when do yo use a paired T-test?
Normally distributed
Comparing dependent samples
Population standard deviation unknown
Small sample size
For a hypothesis test of the mean/ median, when do you use an independent T-test?
Normally distributed
Comparing independent samples
Population standard deviation unknown
Small sample size
When can you say that something is not normally distributed?
Looked at:
Normal plot
Box and whisker plot
Shaprio-wilk
Coefficient of skewness
Transformation can’t be found
What is the test statistic of the sign test?
Z
When can you use the sign test?
Not normally distributed
Test hypothesised median against a sample
What is the more comprehensive alternative to the sign test?
Wilcoxon signed rank test
When do you use the w test statistic for the wilcoxon signed rank test?
When n<25
When can the test statistic for the wilcoxon signed rank test be approximated to the normal (z)?
When n>25
When can you use the Wilcoxon matched pairs rank sum test?
Not normally distributed
Comparing dependent samples
When can you use the Mann-Whitney test?
Not normally distributed
Comparing independent samples
When can you use the normal approximation for the Mann-Whitney test? What test statistic is used otherwise
If n1 or n2 >10
T
What is the main hypothesis test for testing the independence of categories?
Chi-squared test
What is the criteria for using the Chi-squared test?
80% or more of the cells have an expected value >5
All expected frequencies are >1
Total sample size is >20
What can be done for the Chi-squared test if the sample size is too small?
Yate’s correction for Chi-squared test
What hypothesis test for the independence of categories is done if the criteria for Chi-squared are not met?
Fisher’s exact test
Criteria for approximating to the normal in a hypothesis test/ estimation approach for proportions?
Both np and n(1-p) >5
When can the estimation approach for the mean be based on the normal distribution?
Sample from a normal population
Independent observation
Known population standard deviation
Large sample size
Sample not from a normal population
Independent observation
Large sample size
When can the estimation approach for the mean be based on the t distribution?
Data plausibly normally distributed
Independent measurements
Population standard deviation unknown/ small sample size
Correlation coefficient used for normally distributed data?
Pearson’s product moment correlation coefficient
Main correlation coefficient sed for not normally distributed data?
Spearman’s ranked correlation coefficient
What criteria must be met to use pearson’s product moment correlation coefficient?
Both variables normally distributed
Pairs of variables measured on a random sample
Pairs of variables independent
Normally distributed
Comparing one-sample against a reference
Independent samples
Known population S.D.
Large sample size?
For a hypothesis test of the mean/ median, when do you approach using the normal distribution z-score?
Normally distributed
Comparing one-sample against the reference
Independent samples
Population standard deviation unknown
Small sample size
For a hypothesis test of the mean/ median, when do you use the one-sample T-test?
Normally distributed
Comparing dependent samples
Population standard deviation unknown
Small sample size
For a hypothesis test of the mean/ median, when do yo use a paired T-test?
Normally distributed
Comparing independent samples
Population standard deviation unknown
Small sample size
For a hypothesis test of the mean/ median, when do you use a independent T-test?
Not normally distributed
Comparing dependent samples
When can you use the Wilcoxon matched pairs rank sum test?
Not normally distributed Comparing independent samples
When can you use the Mann-Whitney test?
80% or more of the cells have an expected value >5
All expected frequencies are >1
Total sample size is >20
What is the criteria for using the Chi-squared test?
