EPPP Test Construction
Terms
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 What is the item difficulty index(p)?

indicates the percent of examinees in the sample who answerede the item correctly
most situations a p=.50 is optimal except true/false tests where optimal p=.75
the closer that p=.50, the more differentiating the index is  What is item discrimination?
 extent to which a test item discriminates between examinees who obtain high versus low scores on a test
 What is the basis of classical test theory?
 views an obtained test score as reflecting a combination of truth and error
 What is the problem with classical test theory?

items are dependent upon original sample
inability to compare scores obtained on different tests  What is the basis of item response theory?
 involves the use of an item characteristic curve that provides information on relationships between examinee's level on a trait measured by the test and the probability that he will respond correctly to the item
 What are the 3 advantages of item response theory?

sample invariant
possible to equate test scores
easier to develop computeradapted tests  According to classical test theory, what are the components of an examinee's obtained test score?

and true score (T) plus and error component (E)
obtained score (X) = Truth + Error  What does the error component represent in classical test theory?
 represents measurement error which is due to factors that are irrelevant to what is being measured and have an unsystematic effect on the score
 What is normreferenced interpretation?

comparing an examinee's test score to scores obtained by people included in a normative (standardization) sample
helps identify individual differences
percentile ranks, standard scores, age and grade equivalent scores  What is criterion referenced interpretation?
 score interpreted in termso f total amount of test mastered (% correct) or in terms of some external criterion
 What is reliability?
 extent to which test performance is immune to the effects of measurement error
 What is a reliability coefficient?
 indicates whether the attribute measured by the test is being assessed in a consistent, precise way
 How do you interpret a reliability coefficient?

the proportion of variability in obtained test scores that reflects true score variability
reliability coefficient is never squared
r(xx)=true score variablity
1r(xx)=error  What are the different forms of reliability?

testretest (coefficient of stability)
alternate forms (coefficient of equivalence)
splithalf (coefficient of internal consistency)
coefficient alpha (coefficient of internal consistency)
interrater reliability (coefficient of concordance)  What type of reliability is appropriate to measure time sampling error?

testretest (coefficient of stability)
measure attributes that are relatively stable over time  What type of reliability is appropriate to measure time sampling and content sampling errors?

alternate forms (coefficient of equivalence)
not appropriate when attribute measured is expected to fluctuate over time
most rigorous and best method for estimating reliability  Why is alternate forms reliability often not assessed?
 difficulty in developing forms that are truly equivalent
 what are 2 methods for evaluating internal consistency?

splithalf
coefficient alpha  What is the problem with using splithalf reliability?

reliability coefficient based on test scores from onehalf of entire test
reliability tends to decrease as the length of test decreasessplit half usually underestimates test's true reliability  How can you correct for the problems with splithalf reliability?
 use the SpearmanBrown prophecy formulaprovides an estimate of what the reliability coefficient would have been if it had been based on the full length of the test
 When do you use the KuderRichardson Formula 20 (KR20)?

when test items are measured dichotomously
variation of coefficient alpha
not appropriate for speeded tests  What is a drawback of using coefficient alpha?
 lower boundary of a test's reliability
 What is the purpose of using coefficient alpha?
 measure interitem consistency
 When is it appropriate to use interrater reliability?
 whenever test scores depend on a rater's judgement
 When is a kappa coefficient used?
 the reliablity coefficient for interrater reliabliity
 What are the factors that affect the reliability coefficient?

test length
range of test scores
guessing  What is the acceptable level of a reliability coefficient?
 .80 or larger
 What is the standard error of measurement?

an index of the amount of error that can be expected in obtained scores due to the unreliability of the test
calculation of the confidence interval  What is the formula for the standard error of measurement?
 square root of 1r(xx) (reliability coefficient) multipled by the standard deviation of test scores
 What affects the magnitude of the standard error?

standard deviation of test scores and test's reliability coefficient
lower the test's standard deviation and higher reliability coefficient = smaller standard error of measurement  How can you interpret the standard error of measurement?

type of standard deviation
interpret in terms of areas under the normal curve
68%, 95%, 99% confidence intervals 1, 2, 3 standard deviations  What is validity?
 test's accuracy in providing information it was designed to provide
 What are the 3 categories of validity?

content validity
construct validity
criterionrelated validity  What type of validity is important when scores on a test provide information on how much each examinee knows about a domain?
 content and construct validity
 What type of validity is important when scores on a test provide information on each examinee's status with regard to the trait being measured?
 content and construct validity
 What type of validity is important when scores will be used to predict scores on some other measure and you are interested in the predicted scores?
 criterionrelated validity
 What is content validity?
 test items sample content or behavior test was designed to measure
 How do you establish content validity?
 through the judgement of experts
 What type of tests consider content validity to be important?

achievementtype tests
work samples  What additional evidence supports good content validity?

large coefficient of internal consistency
high correlations with other tests that measure the same domain
pre/post test evaluations with a program designed to increase familiarity with material will show changes  What is construct validity?
 the test is found to measure theoretical trait or construct designed to measure
 What are some methods to establish construct validity?

assess internal consistency
study group differences (adequate?)
hypotheseis testingdo the scores change following the experiment
assess convergent (high correlations with the same trait) and divergent (low correlations with different traits) validity
assess factoral validity  What are monotraitmonomethod coefficients?

same traitsame method
correlation between measure and itself
reliability coefficients
should be large  What are monotraitheteromethod coefficients?

same traitdifferent method
correlation between different measures of the same trait
convergent validity  What are heterotraitmonomethod coefficients?

different traitsame method
correlations between different traits measured by the same method
discriminant (divergent) validity  What are heterotraitheteromethod coefficients?

different traitdifferent method
correlation between different traits measured by different methods
discriminant validity when small  What do factor loadings in factor analysis measure?
 square it to determine the amount of variability in test scores explained by the factor
 What is communality in factor analysis?

common variance
amount of variability in test scores that is due to the factors that the test shares in common to some degree with the other tests included in the analysis  From the perspective of factor analysis, what are the components of a test's reliability?

communality
specificity
error  What is the relationship between reliability and communality?
 communality is a lowerlimit estimate of a test's reliability coefficient
 What are the two types of rotation of a factor matrix?

orthogonal
oblique  What type of rotation has uncorrelated factors?
 orthogonal
 What type of rotation has correlated factors?

oblique
attributes measured by the factor are not independent  When can you calculate a factor's communality from the factor loadings?

when factors are orthogonal
communality is equal to the sum of the squared factor loadings  What is a measure of shared variability?
 squared factor loading
 What is criterionrelated validity?
 strong correlation between test and a criterion
 How is criterionrelated validity assessed?
 correlating the scores of a sample of individualson the predictor with their scores on the criterion
 What are the 2 types of criterionrelated validity?
 concurrent & predicitive validity
 What is the difference between concurrent and predictive validity?

the time when the predictor and the criterion are administered
predict future status vs. estimating current status  What is an acceptable level for a validity coefficient?

.20 or .30
rarely exceed .60  How do you interpret validity coefficient?
 since correlation between 2 measuressquare the coefficient and interpret in terms of shared variability
 How do you provide a measure of shared variability?

square the correlation between 2 measures (tests or variables)
how much variability in Y is explained by X  What is the standard error of estimate?
 used to construct a confidence interval around a predicted criterion score
 What is the formula for standard error of estimate?
 square root of 1validity coefficient squared multiplied by standard error of the estimate
 When does the standard error of estimate = 0?
 when the validity coefficient is equal to +/1
 What is incremental validity?

the increase in correct decisions that can be expected if the predictor is used as a decisionmaking tool
involves using a scatterplot  In a scatterplot of criterion and predictor scores, if the goal is to maximize the proportion of true positives, how do you do this?
 set a high predictor cutoff scorewill reduce the number of false positives
 What is the formula for incremental validity?
 positive hit rate  base rate
 What is the base rate?

proportion of people selected without the use of the predictor
dividing successful people (true positive + false negatives) by the total number of people  What is the positive hit rate?

proportion of people who would have been selected on the basis of their predictor scores and who are successful on the criterion
true positives/ total positives  What determines if a person is positive or negative?
 predictor
 What determines if a person is true or false?
 criterion
 What is the correction of attenuation formula used for?

to estimate what a predictor's validity coefficient would be if the predictor and/or criterion were perfectly reliable
tends to overestimate the actual validity coefficient that can be achieved  What information is needed to calculate the correction of attenuation formula?

predictor's current reliability coefficient
criterion's current reliability coefficient
criterionrelated validity coefficient  What happens to the validity coefficient when it is crossvalidated?
 tends to shrink because all of the same chance factors operating in the original sample will not ve present in the new sample
 What is a nonlinear transformation?

whenever a distribution of transformed scores differs in shape from the distribution of raw scoresthe score transformation is this
percentile ranksbecause always flat in shape  What is a standard score?

indicates the examinee's position in the normative sample in terms of standard deviations from the mean
permit comparisons of scores from different tests
zscores
Tscores, deviation IQs, and SAT scores  What is the formula for calculating a zscore?

raw score  mean of distribution
divided by the distribution's standard deviation  What is a linear transformation?
 transformation of raw scores to zscores
 What is the purpose of criterionreferenced (mastery) testing?
 to make sure that all examinees eventually reach the same performance level
 What is a type of criterionreferenced testing?

percentage score
or interpreting test scores in terms of their likely status on an external criterion  When do you use a regression equation and expectancy tape when interpreting test scores?
 criterionreferenced interpretation
 What is banding?
 score adjustment method involves considering people within a specific score range (band) as having identical scores
 What is exploratory factor analysis?
 identify the minimum number of underlying "factors" (dimensions) needed to explain the intercorrelations among a set of tests, subtests, or test items
 What is principal components analysis?
 used to identify a set of variablesthat explains all (or nearly all) of the total variance in a set of test scores
 What eigenvalue is ued to retain components in a principal components analysis?
 1.0 or higher