Qualitative research generates textual data (e.g. comments) while quantitative research provides numerical data (e.g. scores or ratings).

Qualitative research is exploratory in nature. It is used to gain insight into the perceptions and motivations behind observed actions. It is also used to uncover trends in thought and opinions, and explore a question or issue. Common qualitative research methods include focus groups, in-depth interviews (IDIs), and ethnographic observation.

Sample size in qualitative research is usually very small (n=50 or less), and respondents are not selected at random, but to fill a selected quota or target population. Typically, qualitative research focuses on individuals and their impressions. Consequently, studies tend to be iterative, modifying the scope of questions and even target audience as the project unfolds and more insight is gained.

In contrast, quantitative research generates numerical data such as ratings, average scores, response frequencies. It defines attitudes and opinions using statistical inference, generalizing results from a sample to the larger population. Questions are closed-end – there are a pre-defined set of answers from which the respondent chooses. Quantitative data collection methods include surveys (online, intercept, hard copy), face-to-face interviews, longitudinal studies, opinion polls, and systematic observations.

Analysis of quantitative data is statistically driven and includes parametric procedures such as t-tests and ANOVAs to multi-variate techniques such as multiple regression and factor analysis. These type of analyses requires relatively large sample sizes (compared to qualitative research). Quantitative studies often include thousands of respondents.