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Unformatted text preview: interested in? (will use twotail most often but not always) • E.g. 16 cases o Degree of freedom is 15 o Alpha of .05 o Two tail test o Value is 2.131 Calculating the confidence intervals with the tdistribution o CI = ± t x (s/ n ) o Now we need to know both our alpha (usually .05) and our degrees of freedom (DF=n1) o Always use twotail test with confidence interval o Example (student GPAs) n=30 = 2.7 S x = .8 DF = n1 = 301 = 29 t critical = ± 2.045 (from Appendix E3) 95% = ± t (S x / n ) = 2.7 ± 2.045 (.8/ 30 ) = 2.7 ± 2.045 (.146) = 2.7 ± .30 = 2.4 to 3.0...
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This note was uploaded on 03/15/2009 for the course SOCI 301 taught by Professor Kupchick during the Spring '09 term at University of Delaware.
 Spring '09
 Kupchick

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