Technical Report - International Military Testing Association

Teat reliability? -- Certainly 6OmC reliability 4-6 BlCCC66~~ in our
test6 in order to obtain empirical --alidlty. Content validity -- again
we era certainly concerned ,that itema in our tests should adequately cover
the relevant arpect# of job behavior. Eut UC also feel thet there are
only the minimum dcrsirable~ct~aracteri6tic6 thnt a test should have. Our
earlier validation rjtudics asked the question: Doe6 this tC6t pO66e66
anpirical validity? In the present validation procedure, thara 16 no
lOtl@W M empharia !BOlely upon the qu56tiOIl -- he6 this tC6t pO66e68
empirical validity7 -- but more directly urd more appropriatoly, the
qUC6tiOKI is Why is the test valid? and Eov can it6 validity be improved?
. .
As noted in. th‘ra &k&ue paper, 'this one al;o reprer~tr ‘thi
&pplication of itan selection technique6 advocated by CullikrCn in hir
“Theory of Mental TlBSt6." Again, these techniques raqufrs the use of
the point-birerial correlation coefficient for it--tC6t and ittsncriterion
correlat Ions. The specific question v6 ark is, How do each
of there itanr fnflrreoce the validity of the total evaluation test?
The data provided for ita in the preliminary validity report of
our validation sample inclu.de: (a) item p-values, (b) standard deviations,
(c) itar vaclancco, (d) point-biserial itan-total test correlations,
(e) point-birerial itan-criterion correlations, (f) item relitbility
indexes, and (8) itcun validity indexas.
The indexer of rcliability'ami'vrlidfty are obtained by multiplying
the standard devfat:lm of each item by it6 rarpactiva point-birerial
itenwtC8t correlation or point b18crial item-criterion corralatfon.
They reprccrent the contributfon that the ftan maker to the reliability
end the validity of the total toot, respectively.
It is the last concept, the index of vrlidity that nw pO66e66e6
special rignificanccs to our tc6t 8pcciall8t6. By inspection of the
indexer of validity for each it-. they can detcnaine which itaru are at
hart raeking a pori~cive contributim to the validity of the total tt8t,
and inrure their inclu6fou in rubre~.uent te8t rcvirionr. If item
validity indexer are available for each item that 18 includad in a
test, it will be poerible to cetimate the total tart validity before
it 16 � dmini8tered. The paper On itan Mdy8i8 hd6 irlicatsd hw telt
-. .
characteristics ruch a6 the mean, rtandard deviation, and reliability
can be more closely ccntrolled. USC of the item validity index enable8
US to exercire additional control over the mo8t salient feature of a
tart, it8 ability to dircriminatc bctvrcn those lndividual6 vho 8re
.
good and poor performer8 on the job.
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