Is this how a t hypothesis test is done when I don't have the actual data, but just the summarized statistics: > #Homework 9.2.6 [1] > n<-31 > xbar<-3.10 > s_x<-1.469 > m<-57 > ybar<-2.43 > s_y<-1.35 > s_pooled<- (((n-1)*s_x^2) + ((m-1)*s_y^2)) / (n + m - 2) > s_pooled [1] 1.939521 > t_obs <- (xbar - ybar) / (s_pooled * (sqrt(1/n + 1/m))) > t_obs [1] 1.547951 > qt(c(.025, .975), n+m-2) [1] -1.987934 1.987934 > # Therefore, fail to reject H0 at the 0.05 level of significance >
Or am I again overlooking a canned procedure or an easier calculation using the t distribution. Thank you for your continued advice and help. -Kevin [1] An Introduction to Mathematical Statistics and its Applications, fourth ed., Larsen and Marx. Kevin Zembower Internet Services Group manager Center for Communication Programs Bloomberg School of Public Health Johns Hopkins University 111 Market Place, Suite 310 Baltimore, Maryland 21202 410-659-6139 ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
