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You can now run nested crosstabs within Protobi! Hold the Shift key when dragging to nest an additional elements in the banner.

• For an individual tabs, drag an element onto another
• For global tabs tabs, drag an element to the Crosstab button.

Nested crosstabs are useful to untangle confounding across multiple factors.

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For instance, on StackOverflow, a question and answer site for software developers, reputation within the site is correlated with gender but also with years of experience.

The above example shows StackOverflow reputation versus Gender, nested within Years of Experience. We can see here that males are significantly more likely to have higher reputations on StackOverflow, even within similar ranges for experience.

(Note: This is just an example. It certainly does not prove gender drives reputation. StackOverflow reputations increase over time, so early users tend to have much higher reps. In the early years of the site the gender balance seemed far more lopsided than it is even today. But that variable wasn't in this dataset).

To accommodate nesting we've made a few additional changes. First, there are now vertical lines in the table to guide the user's eye. Second, crosstabs are formatted differently for screen versus print, so they print nicely on a page.

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