Google Surveys makes use of the inferred demographic and location information to employ stratified sampling when distributing the surveys to our publisher network and/or Android smartphone users. We infer demographics through respondents' browsing history, then we match them against existing government statistical data. Google Surveys uses post-stratification weighting to compensate for sample deficiencies to remove bias among the survey sample. This gives a more accurate result with lower root mean square error (RMSE), which also makes the results better represent the Current Population Survey (CPS).
Learn more about the differences between representative targeting and convenience targeting, and how each option provides relevant data.