The insight was in knowing to look at differences, week(n) - week(n-1). That was not the raw data. They also noticed that the percentages of "men in favor of

The insight was in knowing to look at differences, week(n) - week(n-1). That was not the raw data. They also noticed that the percentages of "men in favor of Obama" and "women in favor of Obama" did not tend to be odd/even or even/odd numbers. They were even/even or odd/odd. That's obvious only in hindsight.