Research can be done using either qualitative or quantitative data. The decision of which data to use depends on the purpose of the research.
Qualitative Research: Explores an unfamiliar topic, concept, or idea. The data for this research is hard to measure, provided by open ended questionnaires for example. It is presented in the research in descriptive, narrative, exploratory way where a vague topic needs to be clearly defined, explained, the problem should be identified in details.
Quantitative Research: Explores a problem or correlation with variables (measurable data, numbers, or statistics) provided by surveys and questionnaires with closed ended questions for example. Usually uses large samples of data to warrant generalization.
Empirical Research: The terms quantitative and empirical research are often used interchangeably. Empirical research however simply means any form of research that is directly observed. Therefore not all empirical research is quantitative.
Borrowed from the John M. Pfau Library
Examples of Qualitative Vs. Quantitative
Borrowed from the Ebling Library