This article provides an example of how the weighting efficiency statistic is calculated in AskiaAnalyse's weighting report.
When weighting is calculated, a report titled Report of weights.txt can be written to the survey.dat directory (if this directory doesn't exist, it will be created). The report includes a percentage indicating the weighting efficiency, which is an indication of the amount of skewing that had to be done to get the weights to converge; the closer this figure is to 100%, the less skewing needed to be done. An explanation of the weighting efficiency formula can be found here.
Imagine we have 24 interviews in Data.qes. The example file lists, for each interview, the weighting factors in column E. In the range L2:U36, it determines the numbers required for eventually arriving at the weighting efficiency of % 80.05722937.
In WeightingEfficiency.rar there is a .qes and weighted portfolio. If you open this, run the results, and open the file Report of weights.txt in the .dat folder, you should see the following:
Weighting info relates to the weighting options you have set (min weight, max weight, number of possible iterations and accuracy):
The maximum weight displayed in this file is different to what you’ll see in the weighting options, because the base calculated by summing the weighting factors (24.82096438) is different to the unweighted base (24).
If you interview 100 people, and you set your base to be 10,000,000, a “normal” interview would have a weight of 10,000.
If you set the maximum weight to 5, it means the algorithm will ensure the weight will not allocate a weight five times more than a normal interview. In this particular example, it means it will keep all interviews’ weights under 50,000.