Technical Report - International Military Testing Association

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A varietioa of this method would consist of averaging the r-velucr
� ppropriately end compering this average with the raw score standard
deviation.
These methods have two important chorattarirtice in couxon. Fir&,
they lack prtciaioa. The Outoide Critaria, Intra-Itcln Conoiatency, Itan
Hirtory, and Trend Method of checking iton anaiyeie irrvolve limits or
ranges vithin which machine produced it- enalynie data CM vary for rea-
OORO other than error. Although probability estimate6 may be determined
for individual itgls variations within a “range” oc the basis of probrbilfty
tables, the problem would remain as to tha range of probability estimatea
which are apt to lndicata error in the iten enslyair data.
The second camnon charocterietic of imporinnct concerns the expense
involved in these methods. Checking the data, item by item, can be time
consuming end require@ the time and effort of professional personnel.
Extlnple of Interprogram Consistency
A method of checking item analysis which may be called en interprogram
consistency method has the advantages of both speed and prtclafon
for computer application.
This method a8aumta that there are tvo computer programa producing
results on a given set of data. One program mill produce a raw score
mean md standard deviation, and the other the item onalyeia data.
The comparison of the result6 of the two programs 16 baro,d on the
\ relationship of the sum of the item p-vaiues and the raw score mean, and
the � ura of the ites reliabil!..y indicts end the raw &core etandord deviation.
Two further arrumptionr concerning theaa rtatistical characterfrtica
are that r;v ecorea ere computed on the barir of the number of correct
� n8vera and ths;t the item discrimination index io a point-biatriai corrtlatloc
(Gulliksen, 1958).
me computetion of the sum of p and the sum of the reliability
indlcer involves a third cmputer progrem which may be called the itemtent
covariance progrem. The computation0 involvs summing the item pvaluer
(Cp) to product a mean , end the une of the formula
K
L/T-G=
1
to product a rtandard devfation both derived from the itan e~IelyOi8
(Gul’Llkrtn, 1958). The formula dm defines the index (&llikren,
i958).
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