We avoid the false consensus.

Quantitative research generates data and information that can be converted into numbers. Before we begin, we must figure out the number of interviews needed to represent the entire population (i.e. the sample) so we can begin collecting data. We use closed-ended questions, or questions with finite options, to give us an over all big picture and measures how people think about certain issues.

Qualitative research generates non-numerical  data like comments, attitudes, and impressions. We use it to deepen our understanding of specific issues and learn how people refer to certain key concepts. Qualitative research allows participants to express themselves in their own terms.

At most firms, research ends at the qualitative stage. This makes the entire project vulnerable to what psychology calls the false consensus effect—a cognitive bias where people assume their own opinions, beliefs, and values are the norm, and everyone else thinks the way they do. Basically, humans are really bad at predicting the behavior of other humans. In a small group, like a focus group, this bias can quickly turn into a consensus—a false consensus—that may not resonate at all with a target audience on a larger scale.

The best way to avoid the false consensus effect is to take what we learn in focus groups and test it with a broader audience. This is how qualitative research forms the framework for quantitative research.