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Unformatted text preview: Ch. 10- Statistical Inference & Scientific Hypothesis (258) Statistical Hypothesis (260) Statistical Test (262) Hypothesis Testing (264) Steps-(1) state the null and alt. hyp. (2) specify the test statistic&why (3) specify the sample size&the sampling distribution w/ assumptions (4) specify the significance level (5) obtain a random sample of size n ,compute the test statistic&make a decision. Decision Rule (269)- reject the null hypothesis if the test statistic falls in the critical region;otherwise, do not reject the null hypothesis. t statistic (265)- ratio of 2 random var., sampling dist. is the t dist.; approx. normally dist., symmetrical; do not know population standard dev.&must estimate it using the sample standard dev.,derived by Gossett. z statistic-use when testing hypo. about the mean of a single population. Students t distribution & Degrees of freedom (v) (266) Significance level( ) (269) Critical value (270) John Henry effect&Control Groups (273) One-tailed test (275)- directional prediction; stat. test when the critical region is in either the upper tail or the lower tail of samp. dist.; researcher knows a lot about research area. Two-tailed test-nondirectional; in both upper & lower tailes of samp. dist.; only concerned w/ difference not direction; most used test cuz of lack of info. Power (278) Cohens effect size( d ) (281) magnitude of absolute difference; d =|- |/; .2(small).5(medium).8(large). Statistical Significance (282)- due to chance or sampling variability. Practical Significance-useful in the real world. P value (283) Ch. 11- Confidence Interval (293)- Not used as much as null hypothesis testing even though they are more informative. Confidence coefficient-probability (1-); is an open interval (296) b/c the end points are not included. The prob. that a randomly selected interval from this infinite b/c the end points are not included....
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This note was uploaded on 04/30/2008 for the course STATS 2402-04 taught by Professor Kirk during the Spring '08 term at Baylor.
- Spring '08