Glossary of terms used in qualitative research

Survey
The systematic collection, analysis and interpretation of information about some aspect of study. In market research the term is applied particularly to the collection of information by means of sampling and interviews with the selected individuals.
Agency
Any individual, organisation, department or division, including those belonging to the same organisation as the client, responsible for or acting as a supplier on all or part of a research project.
Client
Any individual, organisation, department or division, including those belonging to the same organisation as the research agency, responsible for commissioning or who agree to subscribe to a market research project.
Mystery shopping
The collection of information from retail outlets, showrooms etc, by people posing as ordinary members of the public calling mystery shopping.& Persons who participate the mystery shopping jobs called mystery shopper.
Omnibus surveys
A survey covering a number of topics, usually for different clients. The samples tend to be nationally representative and composed of types of people for which there is a general demand. Clients are charged by the market research agency on the basis of the questionnaire space or the number of questions required.

Glossory for Market research http://www.mrs.org.uk/mrindustry/glossary.htm