What is the most popular medium to do marketing research?

Methodologically, marketing research uses the following types of research designs:

• Qualitative marketing research - generally used for exploratory purposes — small number of respondents — not generalizable to the whole population — statistical significance and confidence not calculated — examples include focus groups, in-depth interviews, and projective techniques
• Quantitative marketing research - generally used to draw conclusions — tests a specific hypothesis - uses random sampling techniques so as to infer from the sample to the population — involves a large number of respondents — examples include surveys and questionnaires. Techniques include choice modelling, maximum difference preference scaling, and covariance analysis.

• Ethnographic studies — by nature qualitative, the researcher observes social phenomena in their natural setting — observations can occur cross-sectionally (observations made at one time) or longitudinally (observations occur over several time-periods) - examples include product-use analysis and computer cookie traces. See also Ethnography and Observational techniques.
• Experimental techniques - by nature quantitative, the researcher creates a quasi-artificial environment to try to control spurious factors, then manipulates at least one of the variables — examples include purchase laboratories and test markets