Quantum normally calculates the standard error and the error variance using the unweighted count of respondents. If you would prefer to use the effective base in the calculation, place the keywords:

on the a statement.

In weighted runs, the standard error (n19) and error variance (n20) of the mean are calculated using an unweighted count of respondents (sum-of-n) rather than the weighted count of respondents. This unweighted value is calculated automatically and is stored as an n15 element with the option nontot to prevent it being included in totals created by n04 or n05 elements.

To calculate the standard error and error variance using weighted figures, place the keywords useeffbase and nsw on the a statement. This tells Quantum to use the effective base rather than the unweighted count of respondents. The effective base is a value that is based on weighted totals but takes into account the possibility that the weighting might have drastically altered the proportion of one group of respondents relative to another. It is calculated as:

An axis can contain more than one block of factors and associated statistics: each block will be dealt with independently.

For more information on the n15 statement, see n15 statement.

For details of the formulae for the mean, standard deviation, the standard error of the mean and the error variance of the mean, see Formulae.

For more information about the effective base and the nsw option, see T statistics on weighted tables.