To print an effective base which does not affect the count in any c=– elements, type:

To print an effective base which does affect the count in any c=– elements, type:

on an n01 or n15 statement.

effbase is not valid on base elements such as n10 and n11. It cannot be used with the base option.

Quantum uses a special base figure, called the effective base, to create T statistics on weighted tables. Without using this special base figure, it is possible that the statistics could produce significant results because the weighting has made adjustments. The effective base takes these adjustments into account and is calculated by dividing the squared sum of weighting factors by the sum of the squared weighting factors.

For more information about the effective base and the formula used for its calculation, see T statistics on weighted tables.

When printing the effective base, you should take into account whether your tables include any special c=– conditions. These conditions can be used to produce a count of respondents who have not been included in any element since the last base in the axis. When making this calculation, Quantum ignores all respondents in the last base element, but includes all respondents in an effective base element created using the effbase keyword. This could result in no one appearing in the c=– element, thus defeating its purpose.

For this reason, Quantum provides two methods for printing the effective base; these are described below.

To define an effective base that does not affect the count in any c=– elements, type:

For example:

To define an effective base when you are not specifying any c=– elements, and so there are no counts that are affected, type:

on an n01 or n15 statement.