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In econometrics, which trades 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, a hypothetical finding that presidential approval rating is approximately equal to twice the percentage of citizens making more than $50,000 annually would predict that the approval rating will be 120% if 60% of citizens make over $50,000. 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 silly to predict an approval rating greater than 100%).
In medical imaging, artifacts are misrepresentations of tissue structures seen in medical images produced by modalities such as Ultrasonography, X-ray Computed Tomography, and Magnetic Resonance Imaging. These artifacts may be caused by a variety of phenomena such as the underlying physics of the energy-tissue interaction (i.e. Ultrasound-air), data acquisition errors (such as patient motion), or a reconstruction algorithm's inability to represent the anatomy. Physicians typically learn to recognize some of these artifacts to avoid mistaking them for actual pathology.
In medical electrophysiological monitoring, artifacts are anomalous (interfering signals) that originate from some source other than the electrophysiological structure being studied. These artifact signals may stem from, but are not limited to: light sources; monitoring equipment issues; utility frequency (50 Hz and 60 Hz); or undesired electrophysiological signals such as EMG presenting on an EEG-, EP-, ECG-, or EOG- signal. Offending artifacts may obscure, distort, or completely misrepresent the true underlying electrophysiological signal sought.
See also 
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- Sonic artifact, in sound and music production, sonic material that is accidental or unwanted, resulting from the editing of another sound.
- Visual artifact, in imaging, any unwanted visual alteration introduced by the imaging equipment.
- Compression artifact, in computer graphics, distortion of media by the data compression.
- See Dictionary.com, definitions 4, 5, and 6. Accessed 2010.05.20.