Artifact (error)
In natural science and signal processing, an artifact or artefact is any error in the perception or representation of any information introduced by the involved equipment or technique.
Statistics
In statistics, statistical artifacts are apparent effects that are introduced inadvertently by methods of data analysis rather than by the process being studied.Computer science
In computer science, digital artifacts are anomalies introduced into digital signals as a result of digital signal processing.Microscopy
In microscopy, visual artifacts are sometimes introduced during the processing of samples into slide form.Econometrics
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%.Remote sensing
Medical imaging
In medical imaging, artifacts are misrepresentations of tissue structures produced by imaging techniques such as ultrasound, X-ray, CT scan, and magnetic resonance imaging. These artifacts may be caused by a variety of phenomena such as the underlying physics of the energy-tissue interaction as between ultrasound and air, susceptibility artifacts, data acquisition errors, 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 ultrasound imaging, several assumptions are made from the computer system to interpret the returning echoes. These are: echoes originate only from the main ultrasound beam ; echoes returns to transducer after a single reflection ; depth of an object relates directly to the amount of time for an echo to reach the transducer ; speed of ultrasound in human tissue is constant, echoes travel in a straight path. and acoustic energy of an echo is uniformly attenuated. When these assumptions are not maintained, artifacts occur.