For Q 4.8.8 or later, the dependent question, independent question, crosstab question, filters and weight may be from two data files, e.g., the dependent question, the first filter and weight may be from data file 1 while the independent question, crosstab question and the second filter may be from data file 2. These two data files must have a one to one relationship specified. Note however that three or more data files are not supported and the variables in the independent question must be from the same data file.
For Q 4.9.1 or later, (positive and negative) signs are applied to driver analysis scores to match the signs of the corresponding linear regression coefficients. Thus the direction of the influence of each independent variable is presented in the scores, in addition to the magnitude. The magnitudes of the driver analysis scores (except for Elasticity) will still be normalized to sum to 100%. Statistical tests are conducted on the signed raw scores, and the value of test statistics may be different from previous versions, resulting in different test results.
As of 1 April 2016, the ability to reuse previous input independent and dependent questions has been removed. In addition, the independent question may no longer be changed in the table. This is due to the discovery of a bug in which these features lead to incorrect data being used in calculations. When running driver analysis, each independent question is constructed specifically for the dependent question that was selected. This is so that missing cases from the dependent question are also marked as missing in the independent question. Therefore independent questions should not be reused in an analysis with another dependent question, otherwise missing cases from the original dependent question will also be missing in the new analysis. This problem will be apparent in the table, as the Base n reported below the table will be smaller than the the actual sample size (which is the number of respondents who have complete data for both dependent and independent variables). Driver analysis tables created prior to 1 April 2016 may be affected if they were created with previous driver analysis questions, or if their independent questions have been replaced in the Blue dropdown, and these can be replaced by:
- Taking note of the Dependent and Independent variables that have been used.
- Right-clicking the table in the Report and selecting Delete.
- Running the appropriate driver analysis option from the Online Library, selecting the same Dependent and Independent variables.
Further reading: Key Driver Analysis Software