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REQUIRED TEXT: Experimental Methodology eighth edition by Larry B. Christensen, Allyn and Bacon, 2001 ISBN #0-205-30832-5 ------------------------------------------------------------ Chapter 13 Hypothesis Testing Scientific Hypothesis: statement of the predicted relationship among the IV – DV. Null Hypothesis: statement of no relationship among IV – DV. No need to memorize any formulas: Mean: Arithmetic average Standard Deviation: measure of disagreement among measurements of DV across participants in the metric of the mean. Can address the question whether group mean differences are psychologically real and interpretable or due to chance. Inferential Statistics: What is the probability that, when repeated, the experiment will end with the same results. Cheaper than repeating the same experiment 100 times. Infer the characteristics of the population from your sample –> Generalization. Estimate the amount of difference that could be expected between the group mean scores by chance and then compare this value with what was actually found. If the actual difference is much greater than what would be expected by chance, we say that the difference is a real one. Are the results due to chance? Two-Tail Tests: 67% of all chance mean difference scores will fall between ±1sd: 95% between ±2 sd from the mean (5 out of 100 will be larger or smaller: 99% between ±3 sd (1 out of 100). At 5% level we will only accept as a real difference one that has a 5 out of 100 chances of occurring by chance. One-Tail Tests: Will only interpret results if they tend in the direction of the hypothesis. ANOVA Reject or fail to reject null hypothesis – never accept the null hypothesis since many unknown but untested variables could produce a real difference if tested. ------------------------------------------------------------ My office is in room 116C of HGH (826-4571) and I invite you to consult with me on any matter during my office hours or any time that is agreeable to you and me.Go back to the beginning
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