Sunday, July 24, 2011

How to choose a statistical test?


Nice table from http://www.graphpad.com/www/book/choose.htm

Table 37.1. Selecting a statistical test

Type of Data
GoalMeasurement (from Gaussian Population)Rank, Score, or Measurement (from Non- Gaussian Population)Binomial
(Two Possible Outcomes)
Survival Time
Describe one groupMean, SDMedian, interquartile rangeProportionKaplan Meier survival curve
Compare one group to a hypothetical valueOne-sample ttestWilcoxon testChi-square
or
Binomial test **
Compare two unpaired groupsUnpaired t testMann-Whitney testFisher's test
(chi-square for large samples)
Log-rank test or Mantel-Haenszel*
Compare two paired groupsPaired t testWilcoxon testMcNemar's testConditional proportional hazards regression*
Compare three or more unmatched groupsOne-way ANOVAKruskal-Wallis testChi-square testCox proportional hazard regression**
Compare three or more matched groupsRepeated-measures ANOVAFriedman testCochrane Q**Conditional proportional hazards regression**
Quantify association between two variablesPearson correlationSpearman correlationContingency coefficients**
Predict value from another measured variableSimple linear regression
or
Nonlinear regression
Nonparametric regression**Simple logistic regression*Cox proportional hazard regression*
Predict value from several measured or binomial variablesMultiple linear regression*
or
Multiple nonlinear regression**
Multiple logistic regression*Cox proportional hazard regression*


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