This question already has an answer here:
I am a bit confused on assigning null and alternative hypotheses.
For example in comparing 2 interventions, conventionally, null hypotheses are usually stating that there are no differences in between both interventions. The alternative hypothesis or what we are trying to prove is that there is a difference between both interventions.
However, what if I want to actually prove or my hypothesis in conducting the study is that the interventions are actually equivalent. Won't the conventional null hypothesis become the alternative hypothesis? Will the conventional alternative hypothesis become the null? Will the statistical tests change since we are now assuming that a difference between study arms is true?