In psychology, research designs test the null hypothesis (H0), and to state it, you would say something to the effect of "There is no difference between this group and that group" or " Variable A has no effect on Variable B". Basically a Null hypothesis is saying that there is no difference, change, or alteration in the group being tested. Because it is easier to prove that there is no change than to prove or disprove change, you test the null hypothesis. You may also want to include an alternative hypothesis, which is the exact opposite of the null and state that change has occurred, it would be worded like "there is a difference between these groups" or "variable A has an effect on variable B". You may also want to do the hypotheses in symbols, which vary by what type of test you are performing and the information you have. hopes this helps and good luck.
