Math Forum :: View topic – statistic

I feel confuse when I did some partice . Anyone correct my calculation if I did wrong? when will I use one-tail test or two tail test? What is the function of P-value and critical value? Example Question: Peter Morgan Forex Ltd. recently conductes a job enrichment program to help increase employee motivation. To test the effectiveness of this program, an organizational psychologist was employeed to administer job motivation tests to two group of employees: those with ‘enriched’ job positions and those without changes in their job positions. Of the 10 selected employees tested after job enrichment, the average score on the motivation test was 28.2 with a standard deviation of 1.32. Among the 16 employees test who had not been affected by the job erichment program, the mean score on the motivation test was 27.5 with a standard deviation of 1.55. At the 0.01 level of significance, is there a significant difference in motivation achieved by the job enrichment program? (Assume the population variance are equal.) My calculation, H0:mean1 – mean2 =0 H1:mean1 – mean2 ≠0 Test Statistic: t n1+n2-2 =(bar X1- bar X2) – ( mean 1- mean2)/ S√1/n1 + 1/n2 t n1+n2-2 =(28.2-27.5)-0 / 1.47√1/10 + 1/16 =1.18 ( inside the acceptance region) I used the t-table to calculate this question because of the small sample and unkown standard deviation. Is it correct? (n1-1) + ( n2-1) (10-1) +(16-1) =24 Therefore t=24 ,then,I checked the t-table row t=0.0005 because of the 0.01 level significance and the colum degrees of freedom= 24, I got 2.797 So,I used two-tail test Therfore H0 is accepted

IfI did wrong,please illustrate the wrong calculation