What is the definition of selection bias in research studies?

Selection bias is defined as a systematic error that occurs when individuals included in a study are not representative of the population that the study intends to analyze. This bias can arise from various factors, such as the methods used for choosing participants, which can lead to certain groups being overrepresented or underrepresented in the sample.

When a study has selection bias, it can compromise the validity of the conclusions drawn from the research, as the results may not accurately reflect the broader population's characteristics, behaviors, or experiences. Researchers strive to minimize selection bias by using random sampling techniques, ensuring that every individual in the population has an equal chance of being included in the study.

The other options do not accurately convey the essence of selection bias. Options stating that it refers to errors in data analysis or describes a situation where participants are randomly selected do not address the representativeness or sampling techniques critical to understanding selection bias.