Systematic Error

Systematic errors result from bias in measurement or estimation strategies and are evident in the consistent over- or underestimation of key parameters. Good survey research methodology seeks to minimize systematic error through probability-based sample selection and the planning and execution of conscientious survey design. There are two key sources of systematic error in survey research: sample selection and response bias.

In the context of survey research, systematic errors may be best understood through a comparison of samples in which respondents are randomly selected (i.e. a probability sample) and samples in which respondents are selected because they are easily accessible (i.e. a convenience sample). Consider, for example, a research project in which the analysts wish to assess attitudes about a town's public library. One [Page 870]way to ...