Cambridge O Level Biology · Syllabus 5090 · Inheritance
Unbiased Sample
What is Unbiased Sample?
A sample chosen in a way that gives every individual in the defined population an equal chance of being included, so that the sample's spread of phenotypes reflects the population's spread. In an investigation into variation, bias is introduced by choosing individuals that are convenient, that are visibly extreme, or that all come from one small part of the habitat, and any of the three makes the resulting distribution unrepresentative however carefully the measurements themselves were taken. Random selection and systematic selection, such as taking every nth individual from a list, are the two standard ways of avoiding it.
This definition is part of the Inheritance chapter in Cambridge O Level Biology.