Volunteer bias

Definition (1):

Volunteer bias is the idea that volunteers for a study are atypical subjects because their self-selection means they will probably be more highly motivated to perform well than people selected at random. This bias, therefore, casts doubt on any generalization made from such a sample to a larger population. This is also a standard weakness of phone-in polls or magazine questionnaires asking for people's views on some issues.

Definition (2):

Volunteer bias means a certain bias that can take place when the subjects who volunteer to take part in a research project vary in some manners from the general population. If it takes place, the researcher samples just a population’s subset, and as a result, the gathered data don’t represent all people, merely represent those who choose to volunteer. This bias is a challenge to any research project’s external validity.

Definition (3):

According to N. Pam M.S., Volunteer bias refers to “any step-by-step variation between involved parties who volunteer to be in an analysis in contrast to those who don't.”

Use of the term in Sentence:

• Suzan expanded the sample and included non-volunteers for avoiding volunteer bias in her research project.