Measurement Issues

Bias, Sampling

In media and market research, a type of selection bias (see “Bias, Selection”) that introduces a systematic error (see “Systematic Error”) due to the inclusive of non-randomly selected individuals in a study population.

Bias, Selection

In media and market research, a type of bias (see “Bias”) where non-representative and/or non-randomly selected individuals make up the population chosen for a study, resulting in data that is skewed. Also referred to as “Selection Effect.” See also “Bias, Sampling.”

Bias, Survey

In media and market research, a bias (see “Bias”) in survey methodology as a result of one or more of the following: biased sampling (see “Bias, Sampling”), a biased survey instrument (see “Bias, Measurement Instrument”) or other flaw in the survey design and/or execution that creates systematic error (see “Systematic Error”) in the survey results and/or interpretation.

Bias, Systematic

See “Bias.” This term is often used interchangebaly with the term “Systematic Error.”


See “Bias, Anchoring.”

Group Effect

A type of bias (see “Bias”) that occurs when participants in a group setting such as a focus group (see “Focus Group”) adapt or change their responses in some way. For example, people sometimes change their responses to match or align with the majority opinion of the group instead of expressing their own opinion. Also referred to as “Groupthink.”


A type of cognitive bias (see “Bias, Cognitive”) that refers to a specific phenomenon that can occur in a group setting (see “Group Effect”) whereby the desire for group cohesion results in a failure of members to think independently and evaluate information objectively, ultimately leading to errors in decision-making. Groupthink has relevance for any media and market research that makes use of groups, such as focus groups (see “Focus Group”).