Because the research and development team knows which cream each volunteer received, the study is at risk of observer bias. Observer bias occurs when an investigator’s evaluation is impacted by knowledge of exposure status.
A bias is a systematic error in a study design. Unlike confounding, a third variable associated with both the exposure and the outcome, a bias cannot be adjusted for in the final analysis. It is important to blind the evaluator in a study design in order to avoid observer bias, especially if the outcome is subjective. Randomization, double-blinding, placebos, and cross-over designs are all strategies to minimize bias. Meta-analyses are specifically at risk for publication bias, a tendency for studies that show an association between an exposure and an outcome to become part of the literature more often than studies which find no association. Meta-analyses with conclusions impacted by publication bias can be later debunked by large trials.
tested for efficacy in a group of 362 healthy 40- to 60-year-old female volunteers. The marketing team randomizes the volunteers. Half receive the new formula and the other half of the volunteers receive the original formula. The mean age in the test group is 48 (95% CI 42-56), and the average age of the control group is 49 (95% CI 42-55). The volunteers are unaware of which formula they receive. The research and development team then compares before and after photographs of the volunteers following 6 weeks of at home application twice daily. For simplicity, the marketing team labels the photographs with “new formula” or “original formula.” 98% of volunteers in the test group complete the study, and 97% of volunteers in the control group complete the study. The researchers conclude that there is improved wrinkle reduction with 6 weeks of use of the new formula. Which of the following potential biases most likely impacted this conclusion?
-
- Selection bias
-
- Hawthorn effect
-
- Observer bias
-
- Procedure bias
-
- Recall bias
0 voters
EXP:
Because the research and development team knows which cream each volunteer received, the study is at risk of observer bias. Observer bias occurs when an investigator’s evaluation is impacted by knowledge of exposure status.
A bias is a systematic error in a study design. Unlike confounding, a third variable associated with both the exposure and the outcome, a bias cannot be adjusted for in the final analysis. It is important to blind the evaluator in a study design in order to avoid observer bias, especially if the outcome is subjective. Randomization, double-blinding, placebos, and cross-over designs are all strategies to minimize bias. Meta-analyses are specifically at risk for publication bias, a tendency for studies that show an association between an exposure and an outcome to become part of the literature more often than studies which find no association. Meta-analyses with conclusions impacted by publication bias can be later debunked by large trials.