Well it depends on the type of research. Qualitative research is useful in circumstances where a marketer would want to gauge feedback from a particular segment of the market or while testing response for a product before launch. while using focus groups, or when studying human behaviour, the quality of data is critical. This has the downside of not being able to represent the whole pool of customers/the whole market.
Quantitative research comes handy in situations like area surveys, or what is known as catchment analysis, where households within a certain kilometer radius are surveyed (for instance before opening of a retail outlet), or while collecting census data. In such situations the numbers matter. More is better. The negatives include data manipulation/fake data, and time(and energy, and money) consuming processes.
