Subtotals allow you to create a net of categories on a categorical variable or a categorical array. This is frequently seen in scale questions (e.g., in ‘top 2 box’ analysis).
Crunch can also allow you to compute differences between categories as well so that you can figure out the difference between the “top 2 box” and, say, the “bottom 2 box”. This is similar to the way NPS™ scores are calculated (Promoters - Detractors).
- With NPS™ scores, many analysts opt for NPS™ recoding (i.e., assigning values of +100, 0, -100) and treating the variable as numeric. This is a perfectly valid way to achieve a difference rating, but the output variable will be numeric (or a numeric array).
- Category differences are exclusive to categorical variables and categorical arrays, with the one exception that category subtotals and differences are not supported for categorical date variables.
Consider the following scale question (in a categorical array):
The brands are the subvariables and the Hate to Love scale represents the categories. A subtotal difference is NET Love:
- The NET Love for Ford calculated as (Love + Like) - (Dislike + Hate). That is, (32% + 42%) - (4% + 7%) = 62%.
How to make and display subtotal differences
You can create and toggle the display of subtotal differences in a very similar way to subtotals.
Currently, you must be a dataset Editor in order to make subtotal differences on public variables. You can make your own differences on private variables (the ones that appear under My Variables at the top of the Variable Tree). This may change in the future. Please refer to Dataset Level User Access for the latest on user permissions.
To create a category difference:
- Go to the Properties of a categorical variable.
- Click Subtotals and differences.
- Click Create Difference.
- Drag and drop the categories you want to include in the positive and the negative boxes respectively (the negative box will be subtracted from the positive box) and then give your difference a name.
- Click Done to commit this change.
- Change the position of the new difference as desired.
- Click Save to exit the Properties window and save the changes.
You can toggle off the display of subtotal differences using the Display Controller.
Frequently asked questions
Can I display category differences in graphs?
No. Like subtotals, category differences do not display in graphs on categorical variables or categorical arrays.
One way around this is to recode it into a numeric variable and then graph the numeric variable/numeric array. Using the above example, you would recode Love/Like to +100 values in a numeric variable, Neutral to 0, and Dislike/Hate to -100. The averages of the resulting numeric variables represent the difference. In the case of Likelihood to Recommend questions, this style of recoding is called NPS™ recoding. The Crunch Automation command CREATE NUMERIC CASE is useful here.
Can I do hypothesis testing with category differences?
Yes, if the difference is in the rows position and a column has been selected for comparison.
Can I have subtotals as well as category differences?
Yes. You can also have as many of each as you like.
Can I edit a category difference after I’ve made it?
Yes. Go back to the Properties > Subtotal and differences and then click Edit on the line for the subtotal difference you want to edit.
Can I selectively show some category subtotals/differences and not others on one variable?
No. You can only display all of them or none of them at once. Remember, you can always make another.
Can category differences be negative numbers?
Yes. You can have negative numbers if the negative scores are greater than the positive scores.