Problem: A human factors psychologist studied three computer keyboard designs. Three samples of individuals were given material to type on a particular keyboard, and the number of errors committed by each participant was recorded. The data are as follows: 5 9 1 6 2 5 Group 1 (Keyboard A) X X Group 2 (Keyboard B) X X2 Group 3 (Keyboard C) X3 X3 1 7 7 6 10 5 1 3 7 2 4 6 = 3 = X2 2 = X3 = X3= mean = mean = mean3 = S = n = 6 S2= n2=6 S3= n3 = 6 1. Identify the IV and the DV. What are the levels of the IV? 2. Write the problem and the statistical/research hypotheses (null and alternate) 3. Fill out the table. 4. Compute SSw, SSB, and SST 5. Create the Summary Table for One-Way ANOVA Sources of Variation Between Within SS DF MS FOBT FCRIT Total 6. Put all the needed values on the table. 7. Test the null hypothesis at .05 level of significance. 8. Write your conclusion in APA format. 9. Determine the effect size. 10. If results are significant, perform the Post-Hoc test. 11. Write conclusions. BES 3146 Statistics for Behavioral Science One-Way ANOVA Practice Worksheet, page 1 Group 1 (Vacation) X X1 Group 2 (Class) X2 Group 3 (Final Exam) X3 X3 2 10 10 3 8 13 7 7 14 2 5 13 6 10 15 = 2 = X2= X2= X3= X3= mean = mean2 = mean3 = S = n = 5 S2= n = 5 S3= n3 = 5 Process Steps: 1. Identify the Independent Variable: 2. What are the levels of the Independent Variable? 3. What is the Dependent Variable: 4. Fill out all the missing items in the table. 5. What is the problem? 6. Formulate the statistical null and alternate hypotheses. 7. Formulate the research hypotheses (null and alternate) 8. What is the level of significance? 9. Determine SSw, SSB, and SST (use formulas on the board) " & SSW = EX+ EX2 + EX3 = [(EX)/n + (EX2)/n2 + [(EX3)/n3] SSB = [(EX1)/n1+ (EX2)/n2 + [(EX3)/n3] - (EX + EX2 + EX3)/N SST = EX+ EX2 + EX3 - (EX+ EX+ EX3)/N == 10. Fill out the Summary Table for One-Way ANOVA Sources of Variation Between SS DF MS FOBT FCRIT Within Total **Transfer computed sums of squares ** *compute DFBETWEEN, DFWITHIN, and DFTOTAL DFBETWEEN K-1 DFWITHIN N-K DFTOTAL N-1 *compute MSBETWEEN and MSWITHIN (MS = SS/DF) **compute FOBT = MSBETWEEN/MSWITHIN **test your null hypothesis 11. Compute Effect Size = SSBETWEEN/SSTOTAL 12. Write results in APA format 13. If results are SIGNIFICANT, proceed to the POST-HOC test (Scheffe Test) The Scheffe Test uses the following formula: 14. Determine adjusted FCRIT FCRIT X (K-1) 15. Write your conclusions. F = (M1-M2)2 MSW (N1+N2)/N1*N2