The researcher cited in the previous problemliguori Robinso

The researcher cited in the previous problem(liguori & Robinson,2001) also examined the effect of caffeine on response time in the driving simulator.In a similar study, researchers measured reaction time 30 minutes after participants consumed one 6-ounce cup of coffee. Using the same driving stimulation task for which the distribution of reaction times is normal with u=40, they obtained a mean of M=392 for a sample of n=36 participants

Solution

=400 msec. and = 40.right?
Test H0 : reaction time = 400 ag. H1 : reaction time not equals 400...
test statistic = ( 392 - 400 ) / ( 40 / sqrt ( 6) ) =  -0.4898979

critical value = + or - 1.96 for a 95% conidence!

0.4898979 < 1.96 and - 0.4898979 > -1.96.
so, we accept H0!
there isn\'t signifiacnt change in reaction time!
cohen\'s d =  ( 392 - 400 ) / ( 40 / sqrt ( 6) ) ( 392 - 400 ) / ( 40 / sqrt ( 6) ) =  -0.4898979

effective sample size = d / sqrt ( d^2 + 4) = -0.4399413