Sign Test for Freshman 15 The table below lists some of the weights from Data Set 4 in Appendix B. Those weights were measured from college students in September and later in April of their freshman year. Assume that we plan to use the sign test to test the claim of no difference between September weights and April weights. What requirements must be satisfied for this test? Is there any requirement that the populations must have a normal distribution or any other specific distribution? In what sense is this sign test a “distribution-free test”?

Solution 1BSC

In order to use the Sign test the only requirement is that the sample data are a simple random sample .The data points should be chosen at random and no priority should be there. As in the given problem the weight of the students are taken at random and not of some particular group of students.

While using the sign test the sign of the differences is taken in to the account. So there is no requirement that the sample data came from a population with any particular distribution, such as normal distribution.

Sign test is a distribution free test; it is used for the data which does not follow any particular distribution, like the normal distribution. Here only the sign of the difference is checked. And the analysis is done on the number of more frequent signs occurring.