Research Bias: A Review For Medical Students

摘要

Bias can be defined as a systematic deviation from what would have been the most effective route to one goal because of commitment to another particular tendency or inclination, especially the one that prevents unprejudiced consideration of a question. A biased study loses validity with respect to the degree of the bias. There are two types of biases which are associated with most forms of research viz Random Bias and Systematic Bias. Random biases are those which occur due to sampling variability or measurement precision, they occur in essentially all quantitative studies and can be minimized but not avoided. Systematic biases are reproducible errors that produce a consistently false pattern of differences between the observed and the true values. Both random and systematic errors can question the validity of any research study. The most common categories of bias that can affect the validity of research include the following: Selection biases, which may result in the subjects in the sample being unrepresentative of the population of interest. Measurement biases, which include issues related to how the outcome of interest was measured. Intervention (exposure) biases, involve differences in how the treatment or intervention was carried out, or how the subjects were exposed to the factor of interest. The common methods that are used to reduce Bias in Research are ? Randomization, Consecutive recruitment, Prospective versus Retrospective Studies and Blinding. Bias is a universal problem which is faced while designing the research study as well as during the execution of the designed research plan and it is well established fact that no study design is exempted from bias.