Artifact (error)

In statistics, statistical artifacts are apparent effects that are introduced inadvertently by methods of data analysis rather than by the process being studied. In computer science, digital artifacts are anomalies introduced into digital signals as a result of digital signal processing. In microscopy, visual artifacts are sometimes introduced during the processing of samples into slide form. In psychology, experimental artifacts are unintentional results caused by distortions or biases in the experimental process. In econometrics, which focuses on computing relationships between related variables, an artifact is a spurious finding, such as one based on either a faulty choice of variables or an over-extension of the computed relationship. Such an artifact may be called a statistical artifact. For instance, imagine a hypothetical finding that presidential approval rating is approximately equal to twice the percentage of citizens making more than $50,000 annually; if 60% of citizens make more than $50,000 annually, this would predict that the approval rating will be 120%. This prediction is a statistical artifact, since it is spurious to use the model when the percentage of citizens making over $50,000 is so high, and gross error to predict an approval rating greater than 100%. In medical imaging, artifacts are misrepresentations of tissue structures produced by imaging techniques such as ultrasound, X-ray, CT scan, and magnetic resonance imaging (MRI).