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> Because the value, as presented, is wrong. That's not true nor is it the problem at all. The thesis was that the values, albeit correct, have too many signif

> Because the value, as presented, is wrong. That's not true nor is it the problem at all. The thesis was that the values, albeit correct, have too many significant digits, which in turn reflect differences which lie somewhere between having no practical use or being absurd. > Imagine, for a moment, that someone uses these values to put up a fence. That example is very poor. Any engineer can tell you that a measurement is meaningless without tolerances/margin of error, and the tolerance in effect when putting up a fence is not expressed in a microscopic scale.

ramshorns 7y ago
> a measurement is meaningless without tolerances/margin of error Reporting a value with too many significant digits is the same as reporting an incorrect margin of error, which (arguably) makes the value wrong.
- seandougall 7y ago
  That's certainly true in a scientific paper, where the concept of significant digits is relevant and widely recognized. In a "please remove dead animal" web request, the value is only wrong if it points to the wrong location (i.e. a location that does not contain a dead animal).
kbutler 7y ago
> Any engineer can tell you that a measurement is meaningless without tolerances/margin of error, and the tolerance in effect when putting up a fence is not expressed in a microscopic scale. But these locations are very precise, indicating high accuracy/low margin of error, but they don't have that high accuracy. In fact, the error could be in meters, rather than in the implied millimeters, so it definitely could be a problem for a fence. Here is a college textbook chapter detailing types of precision and accuracy errors in GIS systems: https://www.e-education.psu.edu/geog469/book/export/html/252 https://www.e-education.psu.edu/geog469/book/export/html/252 "GIS users are not always aware of the difficult problems caused by error, inaccuracy, and imprecision. They often fall prey to False Precision and False Accuracy, that is they report their findings to a level of precision or accuracy that is impossible to achieve with their source materials. If locations on a GIS coverage are only measured within a hundred feet of their true position, it makes no sense to report predicted locations in a solution to a tenth of a foot. That is, just because computers can store numeric figures down many decimal places does not mean that all those decimal places are "significant." It is important for GIS solutions to be reported honestly, and only to the level of accuracy and precision they can support." Or in other words, don't build a fence relying on naked coordinates of high precision but unknown accuracy.

ramshorns 7y ago

> a measurement is meaningless without tolerances/margin of error Reporting a value with too many significant digits is the same as reporting an incorrect margin of error, which (arguably) makes the value wrong.

seandougall 7y ago
That's certainly true in a scientific paper, where the concept of significant digits is relevant and widely recognized. In a "please remove dead animal" web request, the value is only wrong if it points to the wrong location (i.e. a location that does not contain a dead animal).

kbutler 7y ago

> Any engineer can tell you that a measurement is meaningless without tolerances/margin of error, and the tolerance in effect when putting up a fence is not expressed in a microscopic scale. But these locations are very precise, indicating high accuracy/low margin of error, but they don't have that high accuracy. In fact, the error could be in meters, rather than in the implied millimeters, so it definitely could be a problem for a fence. Here is a college textbook chapter detailing types of precision and accuracy errors in GIS systems: https://www.e-education.psu.edu/geog469/book/export/html/252 https://www.e-education.psu.edu/geog469/book/export/html/252 "GIS users are not always aware of the difficult problems caused by error, inaccuracy, and imprecision. They often fall prey to False Precision and False Accuracy, that is they report their findings to a level of precision or accuracy that is impossible to achieve with their source materials. If locations on a GIS coverage are only measured within a hundred feet of their true position, it makes no sense to report predicted locations in a solution to a tenth of a foot. That is, just because computers can store numeric figures down many decimal places does not mean that all those decimal places are "significant." It is important for GIS solutions to be reported honestly, and only to the level of accuracy and precision they can support." Or in other words, don't build a fence relying on naked coordinates of high precision but unknown accuracy.