Combining quantitative and qualitative data

Combining quantitative and qualitative data means using numbers and reasons together. The two types complement each other: quantitative data shows what is happening, such as how many customers buy a product or how often, while qualitative data explains why. On its own, each gives only part of the picture.

For example, a small bakery launches a vegetarian pasty. Its sales records show 300 sausage rolls sold in a week but only 40 pasties — roughly one pasty for every seven sausage rolls. The numbers reveal that the pasty is not selling well, but they do not say why. The baker asks 15 customers who bought a sausage roll what they thought of the pasty. Several did not notice it on the shelf, and some thought it cost more than a sausage roll. The numbers show the size of the problem; the opinions show the cause — poor visibility and a price misunderstanding. The baker can act on both: move the pasty to a clearer spot, add a price label, then check the sales figures again.

Using both gives a fuller picture and a more informed decision. Numbers help a business judge how big a problem or opportunity is, while opinions help it decide what to change. Numbers alone can show a pattern without explaining it, and opinions alone can reveal a reason without showing how many customers share it.