Changing of evaluation under the influence of different factors

The article shows the general notion of evaluation variability. The variability as essential property of evaluation is necessary for keeping the adequacy of everyday evaluations and the accuracy of professional evaluations. Evaluations are changing under the influence of many factors. These factors divided into internal and external, natural and unnatural. Following this it was conducted the analysis of researches that show how different factors influence every evaluation process: reflection of evaluation object, evaluation base, comparison of object with base and expression of evaluation-result.