Introduction
Sometimes there is a need to create weights using data which includes people that screened out of a study. For example, the first two questions may be age and gender and the third question the screener, but there is a need to weight the age and gender to the entire population.
Method
This is done as follows:
- Obtain a data file that includes the data for the respondents that were screened out but need to be taken into account when creating the weight.
- Create the weight.
- In the Variables and Questions tab, right-click on the weight variable and select Copy and Paste Variable(s) > Linked.
- In the Variables and Questions tab, right-click on the new variable and select Convert Formula to Fixed Data.
- Tag the new variable as a weight
- Delete the respondents that screened out.
- (Optionally) If the data file is huge, Save the data as an SPSS data file and the re-import.
Rescaling the weight so that has an average of 1.0
If you wish to rescale the variable so that it has an average of 1.0:
- In the Variables and Questions tab, right-click on the weight variable and select Copy and Paste Variable(s) > Linked.
- Right-click on the newly created variable and select Edit Variable.
- Update the Expression. For example, if the Expression is wQPVSF, and its Mean is 0.0275 (shown at the bottom of the dialog box), your expression would be wQPVSF / 0.0275. (If you wish to compute the average with more decimal places, create a table in the Outputs Tab and increase the number of values.)
- Press OK.
- Tag the new variable as a weight
Automatically completing the above steps
If this process needs to be done automatically as a part of a tracking study this can be done using Access all data rows but this is a very complicated process (as you will need to create the weights using formulas written in JavaScript).
Next
How to Configure a Weight from Variable(s)
How To Create Expansion Weights
How to Combine Weight Variables
How to Automatically Apply Weights to Some Categories in a Banner
How to Use Frequency Weights in Q
How To Set The Weighted Sample Size