In this tutorial
in Example 12.8.1 I understand the result of the test
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## McNemar's Chi-squared test with continuity correction
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## data: right.table
## McNemar's chi-squared = 12.033, df = 1, p-value = 0.0005226
But they conclude that
And in fact, it looks like the ads had a negative effect: people were less likely to vote AGPP after seeing the ads.
How do they know if the effect was positive or negative?