Target weights can be used when you know the exact number of respondents you want to appear in each cell of the weighted table. For example, in a table of age by sex, you might know the exact number of men under 21, women under 21, and so on, to appear in the table once it has been weighted. The weights that you define in your matrix are therefore the values to appear in the weighted table rather than the weights to be applied to each respondent of a given age and sex.

When Quantum creates your weighted table, it calculates the weight for an individual respondent by taking the target figure for the appropriate cell in the weight matrix and dividing it by the number of respondents in that cell.

As an example, suppose that you have three groups of people. The first contains 100 people, the second contains 200, and the third contains 300. You know that in the total population, the spread of any 600 respondents across these three groups would be 150, 200 and 250. When Quantum finds someone in the first group it applies a weight of 1.5 (150/100) to get the total of 150 respondents in the weighted table. Respondents in the second group have a weight of 1.0 because the number of respondents in this group matches the value in the weighting matrix for that group. Respondents in the third group have a weight of 0.83 (250/300) because there are more people in that group than in the corresponding cell of the weighting matrix.

In this example, the number of people in the three groups was the same as the population defined in the weighting matrix. This will not always be the case. Often you might find that the values in the weighting matrix add up to more or less than the number of people that there are in the sample. For example, the spread of the population across the three groups might be 150, 250 and 250, giving a total of 650 respondents. When Quantum balances the sample, it weights each respondent according to the values in the matrix so that the total number of respondents in the weighted table is 650, rather than the 600 that were interviewed.

If you want the total in the weighted table to be the same as the total number of respondents in your sample, define this total as part of the weighting matrix using the keyword total= which is described below. When Quantum reads this keyword, it balances the three groups according to the weights in the matrix and then adjusts all three weights so that the weighted total is 600.

Another variation of target weighting occurs when instead of knowing the actual number of people in each group of the population, you know that each group is a given percentage of the population. For example, the first group might be 27% of the population, the second might be 48%, and the third might be 25%. In cases like this, include the keyword input in the weighting matrix with the percentages for each group.