[Rasch] Units of measurement in the social sciences
trevor.bond at jcu.edu.au
Wed Oct 17 08:57:27 EST 2007
At 11:26 AM -0700 10/16/07, Anthony James wrote:
>Another dumb question...
>I'll be grateful for any comments.
>When we are talking about "units of measurement" in the physical
>sciences we are talking about some tangible things. (I avoide the
>word "concrete" because I know you don't like it in this context and
>argue that all measures are abstractions). However, I mean kilo or
>meter , for example, are understandable attributes that have a
>concerete existence. A "sample meter" ,i.e., a rod of 1 meter can be
>aligned with any object and count the number of alignments. Or we
>can put some potatos on the pan of a scale and put enough weaights
>on the other pan until the beam is balanced.
Sure, there are fundamental measures in the physical science (e.g.
weight, length, volume) which can be physically concatenated as
described by Anthony; but there are other derived physical science
measures (e.g. density, temperature) for which physical concatenation
does not work:
1l water @ 50oC weighs 1kilo and has a density of 1.0
add another identical one to get:
2l water weighing 2kilo with a density of 1.0 and the temp at 50oC
Still - a good (not dumb) question, Anthony!
Trevor G BOND Ph D
Professor and Head of Dept
Educational Psychology, Counselling & Learning Needs
D2-2F-01A EPCL Dept.
Hong Kong Institute of Education
10 Lo Ping Rd, Tai Po
New Territories HONG KONG
Voice: (852) 2948 8473
Fax: (852) 2948 7983
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