[IPAC-List] Speed vs Power Tests

Tue May 31 20:42:15 EDT 2016

I have a vague recollection that Jack Hunter did a factor analysis of some test (GATB?  ASVAB?) where, to his surprise, he found a speed factor independent of g.  It was in a research report; I haven't seen this mentioned in a journal article.
While trying to find this, I noted that John Carrol's three-stratum model (with its fluid and crystallized components) had "broad cognitive speed" and "processing speed" as constructs.  Speed may involve different constructs to be measured.  I'm not familiar with the model, but it seems that everything interrelates, with g as the superordinate stratum.
There's more I stumbled across regarding what is meant by speed or speededness.  This from W.J. van der Linden (2011).  Test design and speededness. Journal of Educational Measurement, 48, 44-60:

"The notion of speededness in testing refers to an interaction between three important factors: the cognitive speed at which the test taker works during the test, the amount of labor required by the items, and the time limit on the test. A test is more speeded when a test taker has to work faster, answering the items requires more labor,and/or the time limit is tightened. As the speed of the test taker is one of these factors, it actually is incorrect to refer to the speededness of a test."
The issue here seems to be that introduction of speededness may introduce a construct other than what was intended.  He continues with an example of someone with a disability not related to the intended construct, but who takes the test slower than others because of the disability.  The speed measured in the test situation may not be the speed in using the intended construct (assuming that speed is intended to be included in the measurement).
Taking the liberty to rephrase Joel's questions, I'm wondering if the speed component is construct contamination or a bonus for g-loaded constructs that are supposedly being measured.  
Somebody please provide answers!

>>> <mhammer at 295.ca> 5/31/2016 6:53 PM >>>
And in keeping with Winfred's comments, the format of each can provide one
with different sorts of measurement of the construct in question; speed
tests being prone to multiple-choice and power more amenable to

Insomuch as speed tests are often a product of convenience contingencies
(e.g., automated scoring), I would think the real question is whether
power tests increment to validity over speed tests.  After all, if there
were a reasonably large number of testees to process, one would opt for a
speed test first since it is less labor-intensive as far as scoring. And
once you have those scores, does an additional power test of some kind
tell you more?

Mark Hammer

> Joel, i think it would have to be a function of the construct assessed,
> right?  so, if by "To what extent do speed and power tests measure the
> same constructs?" you mean the _*same test*_ administered under speeded
> and power conditions, then the answer would have to be "no" b/c
> additional variance, maybe construct-relevant or construct-irrelevant
> has been introduced into the test scores.  consequently, one would
> expect the convergence b/n the two sets of scores to be low
> and "Do speed tests add validity over power tests?" => again, it will
> seem the answer would depend on the constructs assessed by the two
> tests.  thus, for example, tests of processing speed and reaction time,
> are by definition speeded tests; whereas for example tests of fluid
> intelligence (e.g., the Ravens) and declarative knowledge are typically
> better conceptualized as being closer to the power end of the continuum.
> hope this helpful?
> - winfred
> On 5/31/2016 12:34 PM, Joel Wiesen wrote:
>> What is the current thinking on these questions?
>> To what extent do speed and power tests measure the same constructs?
>> Do speed tests add validity over power tests?
>> Thx
>> Joel
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