Artifact (error) - AbsoluteAstronomy.com

In natural science
Natural science
The natural sciences are branches of science that seek to elucidate the rules that govern the natural world by using empirical and scientific methods...

and signal processing
Signal processing
Signal processing is an area of systems engineering, electrical engineering and applied mathematics that deals with operations on or analysis of signals, in either discrete or continuous time...

, an artifact is any error in the perception or representation of any visual

Visual artifact

Visual artifacts are anomalies during visual representation of e.g. digital graphics and imagery.-Examples in digital graphics:* Image quality factors, different types of visual artifacts...

or aural

Sonic artifact

In sound and music production, sonic artifact, or simply artifact, refers to sonic material that is accidental or unwanted, resulting from the editing or manipulation of a sound....

information introduced by the involved equipment or technique(s).

In computer science
Computer science
Computer science or computing science is the study of the theoretical foundations of information and computation and of practical techniques for their implementation and application in computer systems...

, digital artifact

Digital artifact

A digital artifact is any undesired alteration in data introduced in a digital process by an involved technique and/or technology.-Possible causes:...

s are anomalies introduced into digital signals as a result of digital processing.

In microscopy
Microscopy
Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...

, artifacts are sometimes introduced during the processing of samples into slide form. See Artifact (microscopy)

In econometrics
Econometrics
Econometrics has been defined as "the application of mathematics and statistical methods to economic data" and described as the branch of economics "that aims to give empirical content to economic relations." More precisely, it is "the quantitative analysis of actual economic phenomena based on...

, which trades on computing relationships between related variables

Variable (mathematics)

In mathematics, a variable is a value that may change within the scope of a given problem or set of operations. In contrast, a constant is a value that remains unchanged, though often unknown or undetermined. The concepts of constants and variables are fundamental to many areas of mathematics and...

, 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

Approval rating

In the United States, presidential job approval ratings were introduced by George Gallup in the late 1930s to gauge public support for the President of the United States during his term. An approval rating is a percentage determined by a polling which indicates the percentage of respondents to an...

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

X-ray

X-radiation is a form of electromagnetic radiation. X-rays have a wavelength in the range of 0.01 to 10 nanometers, corresponding to frequencies in the range 30 petahertz to 30 exahertz and energies in the range 120 eV to 120 keV. They are shorter in wavelength than UV rays and longer than gamma...

Computed Tomography

Computed tomography

X-ray computed tomography or Computer tomography , is a medical imaging method employing tomography created by computer processing...

, and Magnetic Resonance Imaging

Magnetic resonance imaging

Magnetic resonance imaging , nuclear magnetic resonance imaging , or magnetic resonance tomography is a medical imaging technique used in radiology to visualize detailed internal structures...

. These artifacts may be caused by a variety of phenomena such as the underlying physics of the energy-tissue interaction (ie. Ultrasound-air), data acquisition errors (such as patient motion), or a reconstruction algorithm

Algorithm

In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...

's inability to represent the anatomy. Physicians typically learn to recognize some of these artifacts to avoid mistaking them for actual pathology

Pathology

Pathology is the precise study and diagnosis of disease. The word pathology is from Ancient Greek , pathos, "feeling, suffering"; and , -logia, "the study of". Pathologization, to pathologize, refers to the process of defining a condition or behavior as pathological, e.g. pathological gambling....

.

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 MG presenting on an EEG

EEG

EEG commonly refers to electroencephalography, a measurement of the electrical activity of the brain.EEG may also refer to:* Emperor Entertainment Group, a Hong Kong-based entertainment company...

-, EP

Evoked potential

An evoked potential is an electrical potential recorded from the nervous system of a human or other animal following presentation of a stimulus, as distinct from spontaneous potentials as detected by electroencephalography or electromyography .Evoked potential amplitudes tend to be low, ranging...

-, ECG-, or EOG- signal. Offending artifacts may obscure, distort, or completely misrepresent the true underlying electrophysiological signal sought.

See also