Valintavääristymä

Valintavääristymä, sometimes translated as selection bias, is a systematic error in sampling that occurs when the selection of subjects or data for analysis is not random, leading to a sample that is not representative of the intended population. This can happen in various ways, such as when a particular group is more likely to be included or excluded from a study. For example, a survey conducted only online might exclude individuals without internet access, creating a sample that overrepresents those who are digitally connected. Similarly, if a study on the health effects of a new drug only recruits volunteers who are already enthusiastic about health, the results may not generalize to the broader population.

The consequences of valintavääristymä can be significant, as it can lead to inaccurate conclusions and flawed generalizations. If the selected sample systematically differs from the population of interest in ways relevant to the study's outcome, the observed associations or effects may be misleading. Researchers employ various strategies to mitigate valintavääristymä, including random sampling techniques, carefully defining inclusion and exclusion criteria, and using statistical methods to adjust for known sources of bias. Awareness of potential sources of valintavääristymä is crucial for designing robust studies and interpreting their findings appropriately.