Let us return to the matter of statistical significance: what is it really?

Well, for example, if we find that cats are smarter than dogs, we want to know whether this difference is “real”. Hypothesis testing is how we may answer that question.

We start by converting the question into two hypotheses:

Null hypothesis	(H0)	There is no difference
Alternative hypothesis	(H1)	There is a difference

Note There is no law saying that the null hypothesis is always “no difference” and the alternative hypothesis is always “difference”. However, for the null hypothesis, precedence is commonly given to the “simpler” (or more “conservative” or “normative”) hypothesis. Here, it is generally simpler to claim that there is no difference in intelligence between cats and dogs than to say that there is a difference.