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The effect(s) of such misclassification can vary from an overestimation to an underestimation of the true value. [4] Statisticians have developed methods to adjust for this type of bias, which may assist somewhat in compensating for this problem when known and when it is quantifiable. [5]
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Recall bias is of particular concern in retrospective studies that use a case-control design to investigate the etiology of a disease or psychiatric condition. [ 3 ] [ 4 ] [ 5 ] For example, in studies of risk factors for breast cancer , women who have had the disease may search their memories more thoroughly than members of the unaffected ...
Notable bias (spin) has been reported in the interpretation of results of randomized control trials, although these study designs rank top in the level-of-evidence hierarchy. [36] [37] [38] Contrastingly, a study found low prevalence of bias in the conclusions of non-randomized control trials published in high-ranking orthopedic publications. [39]
Furthermore, another study shows that women are more probable to volunteer for studies than men. [9] Funding bias may lead to the selection of outcomes, test samples, or test procedures that favor a study's financial sponsor. [10] Attrition bias arises due to a loss of participants, e.g., loss of follow up during a study. [11]
Even if a study meets the benchmark requirements for and , and is free of bias, there is still a 36% probability that a paper reporting a positive result will be incorrect; if the base probability of a true result is lower, then this will push the PPV lower too. Furthermore, there is strong evidence that the average statistical power of a study ...
Self-selection bias or a volunteer bias in studies offer further threats to the validity of a study as these participants may have intrinsically different characteristics from the target population of the study. [19] Studies have shown that volunteers tend to come from a higher social standing than from a lower socio-economic background. [20]
Berkson's original illustration involves a retrospective study examining a risk factor for a disease in a statistical sample from a hospital in-patient population. Because samples are taken from a hospital in-patient population, rather than from the general public, this can result in a spurious negative association between the disease and the ...