:2. Solution. That the observed significaance level is 4% does not mean or imply that the chance of the null hypothesis being correct is 4%, nor that the chance of it being incorrect is 4%. It does imply that if the null hypothesis (not the alternative hypothesis!) is true, then the chances of the test statistic turning out to be as extreme or more extreme than it did is only 4%, and so something did happen which had a chance of only one out of twenty of happpening. This is not beyond the bounds of possibility, but is rather difficult to explain as a chance variation.