What is the term for a portion that fairly represents a population by giving each member an equal chance of inclusion?

The term that describes a portion that fairly represents a population by giving each member an equal chance of inclusion is known as random sampling. This method is fundamental in research because it helps ensure that the sample reflects the diversity of the entire population, minimizing the chances of bias that could skew the results.

In random sampling, every individual within the population has an equal opportunity to be selected, which enhances the validity of the research findings since it leads to a more accurate representation of the population as a whole. This approach is essential for making generalizations from the sample to the larger population, thereby improving the reliability of the study's conclusions.

The other options refer to different sampling methods or concepts. Sampling bias occurs when certain members of a population are systematically more likely to be selected for the study, leading to an inaccurate representation. Systematic sampling involves selecting individuals at regular intervals from a randomly ordered list, which may introduce a pattern and can potentially lead to bias if there is an underlying structure in the population. Stratified sampling involves dividing the population into subgroups (strata) and then randomly sampling from each group, which ensures representation from each subgroup but does not give each individual an equal chance of being included overall.