Bias refers to a methodological flaw in a research study which prevents generalization of a sample population out to the entire population. It is a systematic error.
Errors in radiology research studies fall into one of two categories:
- random error
- systematic error/bias
Random error cannot be controlled, but it can be accounted for with the correct statistical technique. An appropriately low p-value improves our confidence that the results are not due to random error (usually set at <0.05 (5%) probability).
Systematic error/bias, on the other hand, cannot be accounted for with statistics. Non-random clustering of variable attributes can flaw our ability to generalize out to the general population. So can non-random gathering of the data by the radiology researcher.
There are multiple opportunities for bias to creep into a radiology study, some obvious and some subtle. It is the researcher's goal to eliminate any large biases and control or account for any smaller ones.
Related Radiopaedia articles
- clinical trials
- descriptive studies
- sensitivity and specificity
- positive predictive value (PPV)
- negative predictive value (NPV)
- likelihood ratio (LR)
- normal distribution
- type I error
- type II error
- confidence interval
- ROC curve
- retrospective studies
- prospective studies
- analyzes of variance
- nonparametric statistics
- cognitive bias in image perception