Technical Report - International Military Testing Association

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&ntroduction
Reliability of Checking Computer
Produced StatfstfcS
CASMER ‘S. WINIEWICZ
US Naval Examining Center
With the advent of computer processing, it became porrible to reduce
large amounts of raw data into more easily handled and more meaningful
forms. Previously, where estimates of the statistical characteristics
of examination6 , such as Iawshe’s D or Flanagan’s r based on eithtr upper
and lover 25 or 27% of a sample wtrt used, it became possible to awitch
to the original point-biserial correlation concept bartd cm the total
samplt. Whtre computer configurations are extended to include a tape
system, it becomes possible to expand the samplt to include the entire
group of examineeo taking a particular examination.
Computer processing, when applied to item analysir, results in
dtcrtated processing time and earlier availability of results. Itan
correlations and difficulty indices based on the total sample result6
in more precise measurement, while the expansion of the sample size to
include the entire population results in even greater stability of
measurement.
Howtver, computer procesring has not been an L;unixtd blessing. With
the onset of any new system, new problems are generated. One of these
problems concerns the introduction of discrepancies into item analyoir
results.
The carue of these discrepancies can be divided into three general
. areas � The first arta could be labeled Program Error. Although new
computer programs are &toted on actual samples of the data they will
process, there is a limit to the exhaustiveness of these ttst8. In
areas of measurement where samples vary in size and characteristics,
unforseen program difficulties may arise.
The stcond arta might be called Machine Error. All machines, even
those components with few or no moving parts, are subject to failure
when used over a period of time. In the read and punch components of
the computtr configuration, burned out circuits may occur, causing a
failure to read or punch out particular card columns. Such discrepancies
are generally consistent in afftcting a particular part of the itan
a.nalyais processed before the failure is discovered. Ir the computtr,
components cooling fans my fall causing over-heating which reeults in
the variable .loea of data. This type of error is the most difficult
to spot by visual inspection because it is variable.
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