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Item formulation psychological testin gfinalxxxx[1]

by MILEN RAMOS

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designing psychological test

designing psychological test

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Item formulation psychological testin gfinalxxxx[1] Presentation Transcript

CONTRUCT VALIDITY 3 ASPECTS SUBSTANTIVE VALIDITY STRUCTURAL VALIDITY EXTERNAL VALIDITY ACCDG TO LOEVINGER THESZE THREE ASPECTS ARE MUTUALLY EXCLUSIVE ,EXHAUSTIVE OF POSSIBLE LINES OF EVIDENCE FOR CONTRUCT VALIDITY AND MANATATORY AND ARE CLOSELY RELATED TO THREE STAGES IN THE TEST CONTRUCTION PROCESS, CONSTITUTION OF THE POOL OF ITEM AND CONSEQUENT SELECTION OF ITEMS TO FORM THE SCORING KEY AND CORRELATION OF TEST SCORES WITH CRITERIA AND OTHER VARIABLES
SUBSTATIVE VALIDITY PHASE IS CENTERED ON THE TASKS OF CONTRUCT CONCEPTUALIZATION AND DEVELOPMENT OF THE INITIAL ITEM POOL review of related literature - important as if the review reveals that there is already a good psychometrically sound measures of the contruct, the scale developer must ask himself whether the new measure is, in fact necessary and if so why however, the existence of psychometrically sound measures of the construct does not necessarily preclude the development of a new instrument
construct conceptualization - 2nd important functrion of the revie is to develop a clear conceptualization of the target construct the literature review will reveal alternative conceptualization of the construct, related contructs that are potentially important and potential pitfalls to consider in the scale development process
development of the initial item pool very critical step in the scale construction no existing data analytic technique can remedy serious deficiencies in an item poor primary consideration during this step is to generate items sampling ALL content that is potentially relevant to the the target construct overinclusiveness - should characterize the initial item pool
relevance - refers to the appropriateness of a measure's items for the target construct principle of content validity - suggest that final decisions regarding scale composition should tale relevance of items into account relevance - refers to the appropriateness of a measure's items for the target construct. when applied to the scale cosntruction process this principle suggest that all items in the finished measure should fall within the boundaries target construct
representativeness- refers to the degree to which the item pool adequately samples content from all important a aspects of the target construct -item pool should contain itemsreflecting all content areas relevant to the target construct -item p[ool should include items reflecting all levels of the trait that need to be assessed classical trait theory - ussually favors selection of items with moderate selection of items with MODERATE endorsement probabilities item response theory - offers valuable tools for quantifying the "trait level" of the items in the pool
item writing item clarity response format use of simple and straightforward language avoid trendy) or colloquial expression avoid complex or convoluted items writing items with stems i worry about .... writing mixture of posivitively and negatively keyed items context neutral
item writing response format dichotomous polytomous use of anchoring schemes based on agreement - strong disagree to strongly agree perceived similarity - uncharacteristic of me to characteristic of me frequency - never to always
pilot testing help identify potential problems such as confusing items or instruction, objecti onable content or the lack of items in an important content area
STRUCTURAL VALIDITY PHASE PSYCHOMETRIC EVALUATION OF ITEMS AND PROVISIONAL SCALE DEVELOPMENT LOEVINGER defined structural component of construct validity as the "extent to which structural relations between test items parallel the structural manifestations of the trait being measured structural relations between test aned nontest manifestation of the target construct should be parallet to the extent possible - structural fidelity
item selection strategies rational theoretical approach - scale developer simply writes items that APPEAR consistent with his or her particular theoretical ` construct pitfalls - discriminant validity suffers replicated rational selection (MMPI2) - involves asking many trained raters (who are given detailed definition of the target construct - to select items from a pool that most clearly tap the construct, given their interpretations of the definition and the items. Only items that achieve a high degree of consensus make the final cut
criterion keyed item selection - items are selected for a scale based solely on their ability to discriminate between individuals from a "normal group and those from a prescribed criterion group. Item content is therefor irrelevant pitfalls- atheoretical and fail to help advance psychological theory in a meaningful way
internal consistency approach to item selection- the goal is to identify relatively homogenous scales that demontrate good discriminant validity accomplished with some variant of factor or component analysis, often combined with classical and modern psychometric approaches to hone factor based scales
data collection psychometric evaluation of items factor analysis- extrem,ely useful to the scale developer who wishes to create homogenous scales t that exhibit good discriminant validity ultimately, however, the most important criterion for choosing factor structure is the psychological and meaningfulmess of the resultant factors good candidate items are those that load at least moderately on the primary factor and minimally on the other factors
internal consistency and homogeneity once a reduced pool of candidate items has been identified through factor analysis, additional item level analysis should be conducted to hone the scales the goals at this stage is to identify a set of items whose intercorrelations match the internal organization of the target construct estimator -- coefficient alpha which are are functions of 2 parameters average interitem correlation number of items on the scale alternatives examination of interitem correlation (.15 to .50) conducting confrimatory factor analysis
item response theory parameter for item difficulty item discrimination item difficulty - also known as threshold or location refers to the point along the trait contimuum at which a given item has a 50 percent probability of being endorsed in the keyed direction discrimination - reflects the degree of psychometric precision or information, that an item provides at its difficulty level standard error of measurement of a scale is equal to the inverse squareroot of information at every point along the trait continuum
‏ IRT method have been used to study item bias or differential item functioning. the basic goal of DIF is to identify items that yield significantly different difficulty or discrimination parameteres across groups of itnerest, after equating groups with respect to the trait being measured IRT application which is potentially relevant to personality is Computerized Adaptive TEsting (CAT) i in which items are individually tailored to the trait level of the respondent A typical CAT selects and administers only those items that provide the most psychometric information at a given ability or trait level eliminating the need to present items that have a very low or very high likelihood of being endorsed or answered correctly given a particular respondent's trait or ability level
EXTERNAL VALIDITY PHASE VALIDATION AGAINST TEST AND NONTEST CRITERIA concerned with two basic aspect of construct validity convergent and discriminant validity criterion related validity whereas the structural phase primarily involves analyses of the items WITHIN the new measure, the goal of the external phase is to examine whether relations between the new measure and the important test and nontest criteria are congruent with one's theoretical understanding of the target construct and its place in the nomologicalnet
convergent validity - extent to which a measure correlates with other measures of the same construct discriminant validity - extent that a measure does not correlate with measures of other constructs that are theoretically or emperically distinct can be assessed by MULTITRAIT-MULTIMETHOD (MTMM) - in such a matrix multiple measures of at least two constructs are correlated and arranged to highlight several important aspect of convergent and discriminant validity
absolute convergent correlations will depend on specific aspects of the measures being correlated concept of method variance - suggest that self rating of the same construct generally will correlated more strongly than will self ratings and peer rating heterotrait-heteromethod triangels -correlation above and below the convergent correlations
convergent validity correlations should be higher than the correlations obtained between that variable and any other variable and any other variable having neither trait nor method in common convergent correlations generally should be higher than the correlations in the hetero- monomethod trianges that appear above and to the right of the heterosexual block the same pattern and trait interrelationship should be shown in all of the heterotrait triangles
criterion related validity concurrent validity- involves relating a measure to criterion evidence colelcted at the same time as the measure itself predictive validity- involves associations with criteria that are assessed at some point in the future GOALS of criterion related confirm the new measure's place in the nomological net provide emperical basis for making inferences from test scores