PSYC105 Lecture Notes - Lecture 5: Statistical Inference, Null Hypothesis, Standard Deviation
11 Oct 2018
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Recap: research question and research hypotheses are always about a population, statistical hypotheses: Alternate hypothesis (h1: basis of inferential statistics: collect data from a sample, generalise conclusions to a wider population. Probability: how likely something is to occur, range from 0 to 1 (0% to 100%) If a variable is normally distributed, we have a lot of information about it. Empirical rule: 68% fall within +- 1 sd of the mean, 95% fall within +- 2 sd of the mean, 99. 8% fall within +- 3 sd of the mean. Intelligence (iq) is normally distributed: mea(cid:374) (cid:894) (cid:895) = (cid:1005)(cid:1004)(cid:1004), sta(cid:374)dard de(cid:448)iatio(cid:374) (cid:894) (cid:895) = (cid:1005)5, say jo has an iq of 115: 1 sd above the mean. Central limit theorem: distribution of sample means will be approximately normal, mean of the sample means will be the same as the population mean, standard deviation of sample means = standard error (se)
