valikueeldus

Valikueeldus, also known as selection bias, is a type of bias that occurs when the selection of participants in a study is not random or representative of the population of interest. This can lead to results that are not generalizable to the broader population, as the sample may not accurately reflect the characteristics of the entire group. Selection bias can arise from various sources, including self-selection, where individuals choose to participate based on their own preferences or circumstances, and non-response bias, where certain groups are less likely to respond to a survey or participate in a study.

There are several types of selection bias, including:

1. Volunteer bias: Occurs when participants volunteer to take part in a study, which may not be representative of the general population.

2. Attrition bias: Happens when participants drop out of a study, and the remaining participants may not be representative of the initial sample.

3. Healthy volunteer effect: Common in medical research, where healthy individuals are more likely to volunteer for studies, leading to an overestimation of the benefits and underestimation of the risks of a treatment.

4. Recall bias: Occurs when participants' memories of past events are influenced by their current knowledge or beliefs, leading to inaccurate reporting.

To minimize selection bias, researchers should aim to use random sampling techniques to ensure that the sample is representative of the population. Additionally, they should consider the potential sources of bias and take steps to address them, such as using propensity score matching or weighting the data to account for differences between the sample and the population. By being aware of and addressing selection bias, researchers can improve the validity and generalizability of their findings.