attrition bias


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attrition bias

A systematic error caused by the selective occurrence and biased handling of protocol deviations and losses to followup, which may lead to results that differ from a study’s true values.
 
Preventive measures
Trialists should ensure low dropout rates, high compliance rates and minimise missing outcomes data.
References in periodicals archive ?
This tool assesses risk of bias within the following domains: selection bias, performance bias, detection bias, attrition bias, reporting bias, and other bias.
Three studies reported data and showed a low risk for attrition bias (Vissers et al.
Our estimates of the influence of single parenthood on children's socioeconomic outcomes are vulnerable to two potential sources of attrition bias.
These results suggest that, despite the higher overall rates of attrition from single-parent families, patterns of attrition bias were virtually identical by family structure, indicating that the most disadvantaged children were lost to follow-up in both two-parent and single-parent families.
Attrition bias can affect the findings of the subsequent rounds of a panel survey, so it is important to examine the extent of sample attrition and determine whether it is random or has affected the representativeness of the panel sample.
If the participating units, however, are not dropped out systematically, meaning that there are no distinctive characteristics among the attriting units, then there is no attrition bias even though the sample has decreased between waves.
1) Among these biases, the attrition bias is somewhat different in that it cannot be controlled solely by the effort of researchers.
However, the review notes, "it is unclear whether alcohol causes a hostile attrition bias or whether it is attributable to an aggressive response pattern learned early in life as all subjects had at least one alcoholic parent.
2 statistical software of The Nordic Cochrane Centre, The Cochrane Collaboration (Copenhagen; 2003), in order to investigate potential attrition bias risk in trials.
However, a possible risk of attrition bias was identified in the results of four datasets (DS 06, 08-10) extracted from two trials [McComb et al.
Researchers evaluating the impact of attrition bias concluded that it generally leads to exaggerated treatment and underreported adverse effects.
Furthermore, this procedure seems to perform better than any other in resolving the attrition bias.