a.Sampling error is measurable while it is not easy to measure a non sampling errors.
b.Sampling error decrease as the sample size increase. This is not necessarily so in the case of a non sampling error.
Conclusion: The researcher should not only be familiar with the forgoing potential errors but should also make an earnest effort to have an effective control over them. His effort should be to ensure that his research study is free form these errors to the extent possible. The is means that he should be ever vigilant throughout the different stages of his research study. However in practice it is seldom possible to eliminate all potential errors. Efforts should be made to minimize individual errors.