Re: Scientific Measurements

Thanks to everyone for all the great information.

The qudt:QuantityValue class [1] from QUDT [2] is really what I've been
looking for to align my current work.

Meanwhile, I wonder how this can be incorporated in schema.org in the long
term?

One wonderful facet of this work is it aligns units of measure against SI
units, giving them standard names, yet allows describing non-SI units.

For the weather data I am working with, it is great to be able to report
data in Celsius units but express a relationship to the SI unit (Kelvin).
 Similarly, for those of us in the USA, there's the additional complexity
of Fahrenheit values.

The one problem is you are required to have a qudt:unit property on
qudt:QuantityValue when I think the common practice would be to have the
qudt:symbol.

That is, we'd have:

  @prefix qudt: <http://qudt.org/schema/qudt#> .
   [ a qudt:QuantityValue; qudt:numericValue "293.15"; qudt:symbol "K" ] .

versus:

   @prefix qudt: <http://qudt.org/schema/qudt#> .
   @prefix unit: <http://qudt.org/vocab/unit#> .
   [a qudt:QuantityValue; qudt:numericValue "293.15"; qudt:unit unit:Kelvin
] .

as this would be more natural to occur in a document:

 <p vocab="http://qudt.org/schema/qudt#"> ... the measured temperature was
<span typeof="QuantityValue"><span
property="numericValue">293.15</span><span
property="symbol">K</span></span> ...</p>

Also, with respect to the symbol values, I see uncommon usages like "degC"
for Celsius rather than ℃.  It is unfortunate that the symbols don't use
the Unicode code point for that but I suppose that can be solved by:

 <p vocab="http://qudt.org/schema/qudt#"> ... the measured temperature was
<span typeof="QuantityValue"><span property="numericValue">20</span><span
property="symbol" content="degC">℃</span></span> ...</p>

Someone please correct me if I've gotten the use of QUDT wrong.  :)

With respect to QuantativeValue, the mapping is:

QuantitativeValue -> like qudt:QuantityValue

   unitCode -> somewhat like qudt:symbol
   value - > qudt:numericValue

but the qudt:unit property is missing.  That concept is a fairly important
if you want to be very precise.

Also, unitCode really needs to be augmented with something that allows
symbols for units of measure rather than UN/CEFACT Common Codes.

A simple change to QuantitativeValue would be:

   * add a 'symbol' property akin to qudt:symbol
   * add a 'unit' property whose expected value is a URI

A further and more complicated change would be to adapt unit descriptions
as a new class but I think having a URI for units allows people to
reference the units defined by vocabularies at qudt.org without completely
replicating that into schema.org.

BTW, Quantitative vs Quantity?  Quantitative = information based in
quantities vs. Quantity = an amount ... Physical sciences deal with
quantities while quantitative reasoning is that based on quantities ...
Yet, we are stuck with the name based on its heritage.

The other option is to create a completely new class for quantities that
has nothing to do with:

   "A point value or interval for product characteristics and other
purposes." (description of QuantitativeValue)

and doesn't attempt to model ranges.  I think that might be confusing to
users.


[1] http://www.qudt.org/qudt/owl/1.0.0/qudt/index.html#QuantityValue
[2] http://qudt.org/

-- 
--Alex Milowski
"The excellence of grammar as a guide is proportional to the paucity of the
inflexions, i.e. to the degree of analysis effected by the language
considered."

Bertrand Russell in a footnote of Principles of Mathematics