Answer:
door-to-door research to gather the data from the target consumers.
Explanation:
A door-to-door research is the process where a researcher visits to interview a respondent at home or in the workplace.... This requires observation of a respondent's living environment if it is agreed in advance. It helps them to get real data in their daily lives on how a particular product is used at home, what they like, how they spend, what they spend on e.t.c.
