nancysara

The first thing is to make a decision on using a one-tail or two-tail test. If you want to compare some product between two companies, then you can go for the two-tail test. If you want to test the performance of a product, then you can go for the one-tail test. The next thing is to identify whether the collected data are one sample, or two sample or more than two samples and you should check the nature of the data: whether it is discrete or continuous. Finally, by selecting the population parameter whether it is the mean, median or the standard deviation. Depending on the population parameter, the statistical test can be performed to find a valid inference. Common practice in every statistical analysis is that if the sample size is small (usually observations less than or equal to 30) then one can use t-test (independent sample, two-sample), fisher’s exact test, etc., depending on the nature of the data. If the sample size is larger, then one may go for z-test, chi-square test, etc.