I believe there are a lot of dangerous assumptions on
http://simia.net/valueparser/
First: there is no indication in a number that it is _not_ endlessly precise.
Apostles = 12
has no uncertainty, representing it as
12 ± 1 is wrong, but also 12 ± 0.5 is wrong.
The same applies to a number like 12.2. The data source and author MAY
desire to express significant digits, but we simply don't know.
Wikidata should keep this at the don't know level and not
force-convert a number of unknown measurement precision to a number
with explicitly stated (but potentially totally wrong) precision or
accuracy limits.
For example, in science it is quite common to give light microscopic
measurement to one decimals behind the micrometer, even though the
precision is 0.2 µm. The latter is simply known and therefore not
constantly repeated, unless specific circumstances justify this.
As discussed above: plus minus 1 s.d. does not give you a confidence
interval for the mean, it gives you a measure of dispersion.
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My proposal: make the default: plus-minus values unknown, only
significant digits known. The interpretation of significant digits is
not machine-available unless qualifiers say so. It can however be used
to result in an estimate of significant digits after conversion.
Make the interval-points an option. If explicitly entered: excellent
information. If not: don't try to create (false) knowledge from void.
Gregor