Quote :

"In major league baseball, American League teams play their games with the designated hitter rule, meaning that pitchers do not bat. The American League believes that replacing the pitcher, traditionally a weak hitter, with another player in the batting order produces more runs and generates more interest among the fans. Below are the average number of runs scored per game by both teams in American League and National League stadiums in the first half of the 2001 season (note that there are 14 teams in the American League and 16 teams in the National League). American League 11.1 10.3 9.4 10.8 10.1 9.3 9.0 10.8 10.0 9.2 8.3 10.3 9.5 9.2 National League 14.0 10.2 9.5 8.3 11.6 9.5 9.1 8.2 10.4 9.5 8.8 8.1 10.3 9.5 8.4 7.9 Do the data suggest that the American League's designated hitter rule results in more runs per game? Perform the appropriate hypothesis test at significance level alpha = .05 and answer the questions below (in all questions below calculate sample means and sample standard deviations to 3 decimal places; do not assume equal population variances except in question 7; use the easy approximation method to approximate the degrees of freedom except in question 7). "

I've been through this problem twice, both manually and with a TI-83, arriving at a t-value of 1.315 both ways using a 2-Sample method...but Webassign grades it as wrong. I would appreciate some direction here.

3/18/2007 8:36:24 PM

did you assume equal population variances. If you did a pooled test that might be your problem.

3/19/2007 8:26:54 AM