hello murray,
here is my take on the abstract provided.
we would not say a thermometer is unreliable in the situation you described
below, but if the thermometer mislabelled a hot day as cold. It would not be
a very valid measure. If it consistently measuered hot days as hot and
measured cold days as cold it would be reliable and valid. If the test
always labelled hot days as cold it would still be reliable but it would no
longer be valid. This paper (based on the abstract) seems to say that range
of motion measures are not reliable either between investigators or with the
same investigator (inter and intra) for measuring people with low back
disorders (if in fact the population of subjects had low back problems). As
you suggest this is not suprising if a week has passed between measures but
within a day you might expect to have some reliability if ROM is a "good
test". On the other hand an SLR to detect nerve root irritation we would
expect not much of a difference between 2 measures 1 day apart if there is
infact nerve root irritation and it is a good test to detect such a
condition. The authors confirm this by concluding that the slr has pretty
good reliability (intra).
In my undrstanding validity speaks of the sensitivity and specificity(among
other things) of a test. Reliablity looks and inter and intra repeat
measures. Precision refers to calibration of the test and the ability of
the test to measure various changes.
John Dufon DC
Peak Rehabilitation
Vancouver, BC
>
>The reference below, provided by a list member, just proves to me once
>again
>that we haven't come to grips with what "reliability" and "variability"
>are. If
>we measure temperature one day, and we get a different temperature the next
>day,
>we don't say the measurement is unreliable. "Reliability", to me, means the
>ability to repeat measurements of a standard and achieve the same result.
>Since
>we aren't measuring a standard, but a moving target, it is difficult to
>interpret reliability. And you can't measure "variability" until you have a
>reliable measure.
>
>Reliability of the Lumbar Flexion, Lumbar Extension, and Passive Straight
>Leg Raise Test in Normal Populations Embedded Within a Complete Physical
>Examination.
>
>Hunt DG, Zuberbier OA, Kozlowski AJ, Robinson J, Berkowitz J, Schultz IZ,
>Milner RA, Crook JM, Turk DC.
>
>
>--
>-*-*-*-*-*-*-*-*-*-*
>
>Murray Maitland
>Assistant Professor
>School of Physical Therapy
>University of South Florida
>12901 N Bruce B. Downs Blvd
>MDC 077
>Tampa Fl USA
>33612-4766
>
>
>Phone (813) 974-1666
>Fax (813) 974-8915
>
>email [log in to unmask]
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