Reporter > Applying statistical tests > Net difference test > Statistical formula for the net difference test > Grid tables
 
Grid tables
For a grid table, it is not possible to display the net difference if the mean is a numeric mean rather than a factor mean. In this case, an error is returned.
For a grid table with factor means:
Notation
Description
X i*
The weighted sum of factors for column i for all respondents belonging in the mean for column i and in the base of column j
X *j
The weighted sum of factors for column j for all respondents belonging in the mean for column j and in the base of column i
Y i*
The weighted sum of squared factors for column i for all respondents belonging in the mean for column i and in the base of column j
Y *j
The weighted sum of squared factors for column j for all respondents belonging in the mean for column j and in the base of column i
Y ij
The weighted sum of (factor for column i) * (factor for column j) for all respondents belonging in the mean for both columns
Using the above terms
where
The degrees of freedom are:
where, for a non-grid, non-overlap table:
and
For a table with overlap or a grid table:
and
For more on the theory of overlapping samples, see Kish, L (1965), Survey Sampling, New York: John Wiley and Sons. ISBN 0-471-48900-X.
See also
Statistical formula for the net difference test