A system is provided for detecting statistical variations and public opinion. The system comprises a respondent interface subsystem for capturing respective opinion values of a set of respondents in relation to a subject matter, said opinion values having respective validity periods associated therewith. The system further includes a database subsystem for storing the respective opinion values corresponding to each respondent and to said subject matter. The system further includes a statistical processing subsystem for calculating successive values of a collected opinion value by selecting respective subsets of said respective user opinion values according to said respective validity periods and calculating said successive values of a collective opinion value over said corresponding subset.