TEST (III)


TEST (III)

The t test (III) is also used with two groups. This test's concern is to find out if the mean of one group is actually different from the mean of the other group . The difference between the t test (II) and the t test (III) has to do with the nature of the two groups. The t test (III) is used only in cases where the two groups are related. When we talk about related groups, we mean groups that are matched on some variable or in which the subjects are used more than once. The requirements for the t test (III) are as follows :

  1. Two groups related

  2. At least interval level of measurement

  3. Populations both normally distributed

  4. Populations having the same variances

  5. Samples drawn at random

The formula used to evaluate whether the difference between these two groups is significant is different from the one used for the t (II). You compute the differences between each pair of scores and then use this difference to estimate the population standard error of the difference.

where = mean of the difference, & pound ; D 2 = square the differences, then find the sum, ( D) 2 = sum the differences, then square the sum, and N = number of pairs of scores.




Six Sigma and Beyond. Statistics and Probability
Six Sigma and Beyond: Statistics and Probability, Volume III
ISBN: 1574443127
EAN: 2147483647
Year: 2003
Pages: 252

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