- False precision
False precision (also called overprecision, fake precision, misplaced precision and spurious accuracy) occurs when numerical data are presented in a manner that implies better precision than is actually the case; since precision is a limit to accuracy, this often leads to overconfidence in the accuracy as well.
In science and engineering, convention dictates that unless a margin of error is explicitly stated, the number of significant figures used in the presentation of data should be limited to what is warranted by the precision of those data. For example, if an instrument can be read to an accuracy of tenths of a unit of measurement, results of calculations using data obtained from that instrument can only be confidently stated to the tenths place, regardless of what the raw calculation returns or whether other data used in the calculation are more accurate. Even outside these disciplines, there is a tendency to assume that all the non-zero digits of a number are meaningful; thus, providing excessive figures may lead the viewer to expect better precision than actually exists.
However, in contrast, it is good practice to retain more significant figures than this in the intermediate stages of a calculation, in order to avoid accumulated rounding errors.
False precision commonly arises when high-precision and low-precision data are combined, and in conversion of units.
- There are numerous variations of a joke which can be summarized as follows: A guard at a museum says a dinosaur skeleton is 70,000,006 years old, because an expert told him that it was 70 million years old when he started working there six years ago.
- "European authorities estimated that the bomb used 220 pounds of explosive." In this example, European authorities, who express measurements in SI units (the metric system), probably estimated that the bomb used 100 kg of explosives. Such estimates are necessarily subject to great uncertainty. When converted by the American media to pounds, the added precision suggests greater accuracy in the estimation of the bomb's size than warranted. A better way to state this is as follows: "European authorities estimated that the bomb used 100 kg (about 220 lbs) of explosives."
- In the United States, normal human body temperature is often quoted as 98.6 °F (37.0 °C). In Russia, the commonly quoted value is 36.6 °C (97.9 °F). These values appear to be the result of the same classic German study that found that the average body temperature of healthy humans is 36.6 °C. Because of the normal variation in human body temperature, this value, if quoted in degrees Celsius and one was not concerned about losing some information, would probably be rounded to 37 °C (implying a precision of the order of 0.5 °C). Converting this rounded value to Fahrenheit gives a value of 98.6 °F; however, quoting the '.6' implies a precision of the order of 0.1 °F, better than warranted by the data.
- ^ "Overprecision". Fallacy files. http://www.fallacyfiles.org/fakeprec.html.
- ^ Mackowiak, Philip A.; Wasserman, Steven S.; Levine, Myron M. (1992), "A critical appraisal of 98.6 degrees F, the upper limit of the normal body temperature, and other legacies of Carl Reinhold August Wunderlich", Journal of the American Medical Association 268 (12): 1578–1580, doi:10.1001/jama.1992.03490120092034 .
- ^ One commonly cited normal range for human body temperature is 36.4 – 37.1 °C (97.5 – 98.8 °F).
- Wong, Lena (1997). "Temperature of a Healthy Human (Body Temperature)". The Physics Factbook. http://hypertextbook.com/facts/LenaWong.shtml.
- Precisely False vs. Approximately Right: A Reader's Guide To Polls
Informal fallaciesAbsence paradox · Begging the question · Blind men and an elephant · Cherry picking · Complex question · False analogy · Fallacy of distribution (Composition · Division) · Furtive fallacy · Hasty generalization · I'm entitled to my opinion · Loaded question · McNamara fallacy · Name calling · Nirvana fallacy · Rationalization (making excuses) · Red herring fallacy · Special pleading · Slothful induction Correlative-based fallacies Deductive fallacies Inductive fallacies Vagueness and ambiguity Equivocation Questionable causeList of fallacies · Other types of fallacy
Wikimedia Foundation. 2010.
Look at other dictionaries:
False dilemma — A false dilemma (also called false dichotomy, the either or fallacy, fallacy of false choice, black and white thinking, or the fallacy of exhaustive hypotheses) is a type of logical fallacy that involves a situation in which only two alternatives … Wikipedia
Precision and recall — are two widely used measures for evaluating the quality of results in domains such as Information Retrieval and statistical classification.Precision can be seen as a measure of exactness or fidelity, whereas Recall is a measure of completeness.In … Wikipedia
False brinelling — is damage caused by fretting corrosion that causes imprints that look similar to brinelling, but are caused by a different mechanism.The basic cause of false brinelling is that lubricant is pushed out of a loaded region. Without lubricant, wear… … Wikipedia
Precision und Recall — Die Artikel Positiver Vorhersagewert und Recall und Precision überschneiden sich thematisch. Hilf mit, die Artikel besser voneinander abzugrenzen oder zu vereinigen. Beteilige dich dazu an der Diskussion über diese Überschneidungen. Bitte… … Deutsch Wikipedia
Precision — Dt. Präzision . Die Qualität von Suchmaschinen Ergebnisse wird u.a. nach Ihre Präzision gemessen. Eine hohe Präzision besagt, dass die gelieferten Ergebnisse der Suchanfrage tatsächlich entsprechen (siehe auch False Drops ) … SEO Wörterbuch
Accuracy and precision — In the fields of science, engineering, industry and statistics, accuracy is the degree of closeness of a measured or calculated quantity to its actual (true) value. Accuracy is closely related to precision, also called reproducibility or… … Wikipedia
Arithmetic precision — The precision of a value describes the number of digits that are used to express that value. In a scientific setting this would be the total number of digits (sometimes called the significant figures or significant digits) or, less commonly, the… … Wikipedia
Recall und Precision — Die Artikel Positiver Vorhersagewert und Recall und Precision überschneiden sich thematisch. Hilf mit, die Artikel besser voneinander abzugrenzen oder zu vereinigen. Beteilige dich dazu an der Diskussion über diese Überschneidungen. Bitte… … Deutsch Wikipedia
Recall und precision — Die Artikel Positiver Vorhersagewert und Recall und Precision überschneiden sich thematisch. Hilf mit, die Artikel besser voneinander abzugrenzen oder zu vereinigen. Beteilige dich dazu an der Diskussion über diese Überschneidungen. Bitte… … Deutsch Wikipedia
Ambiguity — Sir John Tenniel s illustration of the Caterpillar for Lewis Carroll s Alice s Adventures in Wonderland is noted for its ambiguous central figure, whose head can be viewed as being a human male s face with a pointed nose and pointy chin or being… … Wikipedia