It's certainly true that there is a semantic problem, with people
interpreting terms in different ways. (So what's new?)
Having started life (so to speak) as a mathematician, a 'scale' is a
characteristic of the variable being measured. The construct that a
couple of people have referred to as a 'Likert scale' I would call a
'variable' (or possibly 'measure'). The range of possible values, and
the way they are laid out (eg, for 0 to 100, hopefully 'interval' or
even 'ratio') forms the scale for this variable.
The common usage of 'Likert scale' to mean an ordinal scale, usually
from 1 to 5, usually expressing level of agreement with a proposition
fits this view of the terms. An individual item of this type defines a
variable, and this variable has a Likert scale, in this sense of the
term. The composite variable or measure (hopefully) has a reasonably
numeric scale.
Regards,
Alan
Dennis Roberts wrote:
>
> we do have a semantics problem with terms like this ... scale ... and
> confuse sometimes the actual physical paper and pencil instrument with the
> underlying continuum on which we are trying to place people
>
> so, even in likert's work ... he refers to THE attitude scales ... and then
> lists the items on each ... thus, it is easy to see an equating made
> between the collection of items ... nicely printed ... BEING the scale ...
>
> but really, the scale is not that ... one has to think about the SCORE
> value range ... that is possible ... when this physical "thing" (nicely
> printed collection of items) is administered to Ss ...
>
> thus ... for 10 typically response worded likert items with SA to SD ...
> the range of scores on the scale might be 10 to 50 ... of which any
> particular S might get any one of those values somewhere along the continuum
>
> but of course, scale is even "deeper" than that since, what we really have
> is a psychophysical problem ... that is, what is the functional
> relationship that links the physical scale ... 10 to 50 ... to the
> (assumed to exist) underlying psychological continuum ...
>
> PHYSICAL SCALE 10 (NEGATIVE) <--------------------------------> 50
> (POSITIVE)
>
> PSYCHOLOGICAL
> CONTINUUM MOST NEGATIVE <-------------------------------->
> MOST POSITIVE
>
> problems like ... do equal distances along the physical scale ... equate to
> the same and equal distances along the psychological continuum? is there a
> linear relationship between these two? curvilinear?
>
> so, i think what we really mean by scale is this construct ... ie, the
> psychological continuum ... and a scale value would be where a S is along
> it ... but, about the best we can do to "assess" this is to see where the S
> is along the physical scale ... ie, where from 10 to 50 ... and use this as
> our PROXY measure ...
>
> BUT IN any case ... i think it is helpful NOT to call the actual instrument
> ... the paper and pencil collection of items ... THE scale ...
>
> _________________________________________________________
> dennis roberts, educational psychology, penn state university
> 208 cedar, AC 8148632401, mailto:[EMAIL PROTECTED]
> http://roberts.ed.psu.edu/users/droberts/drober~1.htm
>
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--
Alan McLean ([EMAIL PROTECTED])
Department of Econometrics and Business Statistics
Monash University, Caulfield Campus, Melbourne
Tel: +61 03 9903 2102 Fax: +61 03 9903 2007
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