a) Sometimes a study is unable to find an effect in a particular sample, called a ‘null result’. Please speculate the possible reasons for null results (1 point). Is there any way that a researcher may pre-emptively plan their research endeavour in such a way that they reduce the chances of having a null result?

b) You were asked to use a χ² test of independence, which is a non-parametric test. Please describe the difference between a parametric and a non-parametric test (2 points), and state when it is most appropriate to use each one (1 point).