Quantitative research is generally regarded as the most reliable source of information since it always involves the use of numbers, often uses calculations and derives concrete facts through careful observations and creative analyses. Some believe that mathematical findings and laws are the closest things to truth that science can ever hope to approach. Quantitative data consists of numbers, figures, percentages, dollar amounts and measurements. The finite nature of quantitative results is attractive to research investors, and the costs of performing quantitative research are generally far lower than employing complex qualitative methods.
Qualitative methods allow scientists to explore complex questions, including value-laden inquiries and subjective information. Data is often collected through in-depth one-on-one interviews, surveys or small focus groups in order to explore an issue more fully and with less restriction. This ability of qualitative methods to look holistically at a problem has led to its increased use in research, especially in the social sciences. In psychology, for example, many questions concerning the brain cannot be quantified, such as how a person thinks or feels.
Qualitative research provides researchers with insights into group behavior by revealing relationships between different dimensions of group interactions. Quantitative research may be able to accurately tell researchers how many people in a given area are smokers or how many smokers die from smoking, but qualitative research is necessary to explore the reasons why people smoke. Stress, peer pressure, addiction and boredom are all qualitative responses that add another dimension to the understanding of why people continue to smoke.
By exploring the motivations, emotions, thoughts and experiences that cause an individual or group's behavior, researchers are led to new questions and ideas for follow-up research. Qualitative research expands knowledge and understanding of the world by building upon and strengthening new and existing theories. Many scientists agree that the perfect experiment design would involve a combination of both quantitative and qualitative methods to arrive at the best-possible understanding of the problem.