Selection bias

Selection Bias is a type of bias that occurs when the sample used in a study is not representative of the population from which it was drawn. This can lead to inaccurate results and conclusions, as the sample may not accurately reflect the characteristics of the population.

Definition

Selection bias refers to the practice of selectively choosing data or data sets in a way that leads to a conclusion that is misleading or distorted. This can occur in a variety of ways, such as when samples are selected in a non-random manner, when there is a lack of randomization in the assignment of treatments, or when there is a differential loss of participants from the study.

Types of Selection Bias

There are several types of selection bias, including:

• Sampling bias: This occurs when the sample used in a study is not representative of the population from which it was drawn. This can lead to inaccurate results and conclusions, as the sample may not accurately reflect the characteristics of the population.

• Time interval bias: This occurs when the time period chosen for a study influences the results. For example, a study on the effects of a new drug might only include patients who have been taking the drug for a certain period of time, excluding those who have recently started or stopped taking the drug.

• Data bias: This occurs when the data used in a study is not representative of the full data set. This can occur if certain data is excluded or if the data is not collected in a consistent manner.

Effects of Selection Bias

Selection bias can have a significant impact on the results of a study. It can lead to inaccurate conclusions and can potentially mislead researchers and policymakers. It is therefore important to take steps to minimize selection bias in research studies.

Minimizing Selection Bias

There are several strategies that can be used to minimize selection bias, including:

• Using random sampling techniques to select participants for a study.
• Ensuring that all eligible individuals have an equal chance of being selected for the study.
• Using statistical methods to adjust for potential selection bias.

See Also

• Bias (statistics)
• Sampling (statistics)
• Randomization

Selection bias Resources
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