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For weighted analyses, the t statistic is computed as
Note | The t statistic and p-value are set to missing if vardefDF. |
The Sign statistic is
The Signed Rank test assumes that the distribution is symmetric. The signed rank statistic is computed as where r^{+}_{i} is the rank of after discarding y_{i} values equal to , and the sum is calculated for values of .Average ranks are used for tied values. The p-value is the probability of obtaining a signed rank statistic greater in absolute value than the absolute value of the observed statistic S. If n_{t} <= 20, the p-value of the statistic S is computed from the exact distribution of S. When n_{t} > 20, the significance level of S is computed by treating
as a Student's t variate with n_{t}-1 degrees of freedom, where V is computed as
The sum is calculated over groups tied in absolute value,
and t_{j} is the number of tied values in the
jth group (Iman 1974, Lehmann 1975).
You can specify location tests either in the distribution output options dialog or in the Location Tests dialog after choosing Tables:Tests for Location from the menu.
In the dialog, you can specify the parameter .Figure 38.11 shows a table of the three location tests for = 60. Here, Num Obs != Mu0 is the number of observations with values not equal to , and Num Obs > Mu0 is the number of observations with values greater than .
For weighted analyses, the sign and signed rank tests are not generated.
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