Valikoitumisvirhe

Valikoitumisvirhe, also known as selection bias, is a systematic error that can occur when the individuals or groups selected for a study are not representative of the population that the researchers intend to study. This discrepancy leads to an inaccurate or misleading conclusion about the population. It arises because the selection process itself favors certain outcomes or individuals over others.

There are several common forms of valikoitumisvirhe. For instance, self-selection bias occurs when participants choose to be part of a study, and those who volunteer may differ systematically from those who do not. This is often seen in online surveys or studies that rely on voluntary participation. Another type is attrition bias, which happens when participants drop out of a study, and their reasons for leaving are related to the study's outcome. If those who drop out have a different experience or characteristic than those who remain, the remaining sample may no longer be representative.

Healthy user bias is a specific instance where individuals who adopt a healthy lifestyle tend to participate in health studies more often than those who do not. This can create a false impression that a particular intervention or lifestyle choice is more effective than it actually is, simply because the participants are already healthier. Recognizing and mitigating valikoitumisvirhe is crucial for ensuring the validity and generalizability of research findings. Researchers employ various methods, such as random sampling and careful matching of control groups, to minimize its impact.