Goal of tests of significance: to assess the evidence provided by data about some claim concerning the population. Pro(cid:448)ide e(cid:448)ide(cid:374)ce agai(cid:374)st a clai(cid:373): (cid:862)a(cid:374) outco(cid:373)e that (cid:449)ould rarely happen if a claim is true is good e(cid:448)ide(cid:374)ce that the clai(cid:373) is (cid:374)ot true(cid:863) Conditions must be true: srs, normal population, standard deviation known to us. We make a claim, ask if the evidence proves against it: if we want to know if the mean is under a certain level, then the claim we test is that the mean is at that level. Observed effect= observed statistic claimed parameter value. Statistically significant: an observed effect is too large to plausibly to due to chance variation. Null hypothesis: the claim tested by a statistical test. Alternate hypothesis: the claim about the population that we are trying to find evidence for. Hypotheses refer to a population, not to a particular outcome.