parameters: 7,1,6,3,6,7. A. Whats the sample mean? B. Whats the SS for these scores? C. Whats the sample standard deviation? D. Whats the standard error? E. Whats the differein between the formula for calculating z and t?
B. SS ( sum of squares ) = (7-1)^2 + (5-1)^2 + (5-6)^2 + (5-3)^2 + (5-6)^2 + (5-7)^2
=. 4 + 16 + 1 + 4 + 1 + 4
C. sample standard deviation = S = sqrt ( 34) = 5.83
D. Standard error of the mean = mean/sqrt (n) = 5/sqrt(6) = 5/2.45 = 2.04
E. z score is used when the standard deviation of the population is known. t statistic is used when the standard deviation of the population is not known. So in the formula for the z score you use the mean and the standard deviation of the population whereas for the t statistic formula the sample mean and the standard error is used.