A good research is the one
that is valid and reliable.
One of the ways to test the reliabilty of the survey is to conduct it again under the same conditions with the same design and obtain the same results. But due to its financial and time cost, surveys are not repeated for this puropose. But the public opinion polls done to estimate the election results are tested by the election results. In other words, the election serves as a lab for the polls.
Yönelim has been assigned to conduct public opinion polls to estimate the election and referandum results since its foundation. And it has been one of the organizations making the best estimations. The surveys of Yönelim have been tested.