There are two main approaches to research - quantitative and qualitative. Quantitative emphasizes numbers, measurements, and experimentation, while qualitative emphasizes natural settings, observations, and interpretations. The goals and designs of the two approaches also differ, with quantitative aiming to test hypotheses and qualify aiming to build theory. Sample sizes, data collection methods, and types of data also tend to differ between quantitative and qualitative research. Mixed methods research involves using elements of both quantitative and qualitative research.