Advanced tables and statistics > Special T statistics > Requesting a test > Checking how Quantum calculated your statistics
 
Checking how Quantum calculated your statistics
Sometimes you might be surprised by the results of your tests and want to check how Quantum arrived at a value. Use the keyword debug on the tstat statement to make Quantum write the intermediate figures it uses to calculate the statistics. This information is written to a file called tstat.dmp. For example:
Props for row (#1) "Brand A"
COL        SUM(W)      SUM(WX)    SUM(WX2)     SUM(W2)       EFFBA
 A      125.000000    16.000000   16.000000  125.000000  125.000000
 B      312.000000   128.000000  128.000000  312.000000  312.000000
COLS    SUM(W) SUM(WX1) SUM(WX12) SUM(WX2) SUM(WX22) SUM(WX1X2) SUM(W2)
A B   0.000000 0.000000  0.000000 0.000000  0.000000  0.000000 0.000000
TEST    P1       P2       CORR    S.E.    D.O.F. RISK QCRIT      QVAL
A B 0.128000 0.410256 0.000000 0.049813 436.0000 0.05 2.770 -8.013446
     TVAL      PVAL
 5.666362  0.000000
The values in this report are as follows. The first section refers to all respondents in the row being tested:
SUM(W)
The sum of weights for column A, shown as wk in the formulae.
SUM(WX)
The sum of (weights times factors) for column A, shown as
in the formulae. Factors are 1.0 for all tests except the test on column means.
SUM(WX2)
The (sum of (weights times factors squared)), shown as
in the formulae. Factors are 1.0 for all tests except the test on column means.
SUM(W2)
The sum of squared weights. Shown as
in the formulae.
EFFBA
The effective base. Shown as ek in the formulae.
The second section refers to respondents who have overlapping data in the row being tested:
SUM(W)
The sum of weights for overlapping data in column A, shown as wo in the formulae.
SUM(WX1)
The sum of (weights times factors) for overlapping data in column A. Factors are 1.0 for all tests except the test on column means.
SUM(WX12)
The (sum of (weights times factors)) squared for overlapping data in column A. Factors are 1.0 for all tests except the test on column means.
SUM(WX2)
The sum of (weights times factors) for overlapping data in column B. Factors are 1.0 for all tests except the test on column means.
SUM(WX22)
The (sum of (weights times factors)) squared for overlapping data in column B. Factors are 1.0 for all tests except the test on column means.
SUM(WX1X2)
SUM(WX1) times SUM(WX2).
SUM(W2)
The sum of squared weights.
The third section refers to the test itself:
P1
For a proportions test, the proportion in column A. For a means test, the value is labeled MEAN1 and shows the mean for column A.
P2
For a proportions test, the proportion in column B. For a means test, the value is labeled MEAN2 and shows the mean for column B.
CORR
The correlation co-efficient.
S.E
The standard error.
D.O.F.
The degrees of freedom.
RISK
The risk level requested for this test (100–clevel).
QCRIT
The critical value of the Student t distribution times .
QVAL
The value calculated by the statistic.
TVAL
The T-value calculated as QVAL divided by .
PVAL
The P-value.
To see this type of information for all special T statistics in a run, put tstatdebug on the a statement and omit debug from the individual tstat statements.
See also
Requesting a test