how is the null hypothesis identified 
the analyst or researcher establishes a null hypothesis based on the research question or problem they are trying to answer depending on the question the null may be identified differently for example if the question is simply whether an effect exists e g does x influence y the null hypothesis could be h0 x 0 if the question is instead is x the same as y the h0 would be x y if it is that the effect of x on y is positive h0 would be x 0 if the resulting analysis shows an effect that is statistically significantly different from zero the null can be rejected 