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CLT stands for Central Local Test (also known as Hall Test) and it’s a quantitative or qualitative type of data collection that requires the physical presence of the interviewee and interviewer in a special venue that has PCs connected to Internet, usually inside a mall, department store or in other such public places. Interviewees are either recruited in advance or on the spot.


DataDiggers runs CLT projects in all the countries where we own proprietary online panels (Bulgaria, Croatia, Czech Republic, Greece, Hungary, Poland, Romania, Serbia, Slovakia and Turkey), as well as around the world via carefully chosen local partners.

Our local suppliers have access to special CLT venues in major cities of each country of field, usually the capital + a few others large cities.

The online link used to collect data can either be provided by client or our team can program it internally using specialized software.

Quality control

We employ several methods to ensure best quality for the data collected using CLT methodology:

  • Apart from the project manager that is in permanent contact with client, two senior level local supervisors work on each project, ensuring backup throughout the project and availability of a knowledgeable contact at all times
  • Project materials are proofed for translation by native speakers of each language, to make sure that client’s original goals are not missed due to poor translation
  • Before starting the fieldwork we run an internal quality review of the questionnaire to check the accuracy and make suggestions to client if necessary
  • Interviewers are always briefed before starting the fieldwork, with a special focus on B2B projects, so that they accurately understand project’s challenges and requirements
  • Internal validation of at least 10% of interviews
  • Deliverables are thoroughly checked by two different experienced analysts to ensure accuracy before they are sent over to client.

Works best for ...

  • Projects that require various tests on the spot: product tests, packaging tests, sniff tests
  • Testing commercials
  • Audiences that are hard to reach in an online panel

Looking for a high quality provider of CLT services?