The bread and butter of statistical analysis "t-test": Uses and misuses

Statistical tests are very important in biomedical research.1 Several factors play a role in selecting the most appropriate statistical test.2 The misuse or inaccurate use of a statistical test may navigate the research in the wrong direction, and hence incorrect conclusions. Because it is probably the most commonly used statistical test, Student's t-test is considered "the bread and butter" of statistical analysis. The William Gossett test "Student's t-test" is easy to use, however, it is also misused.3 There are three types of the t-test, which are used for comparing either a single mean or two population means (Table-I). Each t-test can be used under specific conditions and criteria.

Types of t-test:

1. One- Sample t-Test

It is used for comparing sample results with a known and specified value, sometimes a "gold standard". The task of this test should be to answer the question "is the mean of the population from which the sample is taken is different from the specified value"? For example, based on a random sample of 200 students, can we conclude that the average IQ score this year is lower...