That's a good point, you don't always know, so your quantitative data starts with qualitative (you decide what to measure). But, for the common cases you can f

That's a good point, you don't always know, so your quantitative data starts with qualitative (you decide what to measure). But, for the common cases you can follow the industry standard measurements. They also learned from the war question mentioned in the article, now they just measure public support, too.