what is a non sampling error 
a non sampling error is a statistical term that refers to an error that results during data collection causing the data to differ from the true values a non sampling error differs from a sampling error a sampling error is limited to any differences between sample values and universe values that arise because the sample size was limited the entire universe cannot be sampled in a survey or a census a sampling error can result even when no mistakes of any kind are made the errors result from the mere fact that data in a sample is unlikely to perfectly match data in the universe from which the sample is taken this error can be minimized by increasing the sample size non sampling errors cover all other discrepancies including those that arise from a poor sampling technique 