MeasurementChapter 8 Cooper and Schindler

MeasurementConsist of assigning numbers to empirical events in compliance with a set of rulesThe definition implies that measurement is a three-part processSelecting observable empirical eventsUsing numbers or symbols to represent aspects of the eventsApplying a mapping rule to connect the observation to the symbolExampleStudying people who attend an auto show where all of the years new models are on displayGenderStyling characteristics

Characteristics of MeasurementEmpiricalObservationsMapping RuleSymbolGenderStyling CharacteristicsMF14235A B C D EA B C D EGenderof showattendeesA-EAssignM if maleF if femaleDesirabilityof styling toshow attendeesA-EAssign5 if Very Desirable4 if Desirable3 if neither2 if undesirable1 if Very Undesirable(1 through 5)

What Is Measured? (I)ConceptsObjectsInclude the things of ordinary experience, such as tables, people, books and automobilesAlso include things that are not as concrete, such as genes, attitudes, neutrons and peer-group pressuresPropertiesAre the characteristics of the objectsPhysical propertiesPsychological propertiesSocial propertiesResearchers measure indicants of the properties of objects

What Is Measured? (II)Age, Years of experience, Number of calls per weekIt is not easy to measure properties Motivation to succeed, ability to stand stress, problem-solving ability, and persuasivenessThere is often disagreement about how to operationalize the indicantsNot only is it a challenge to measure such constructs, but a studys quality depends on what measures are selected or constructed, and how they fit the circumstances

Scale ClassificationsEmploy the real numbers systemsThe most accepted basis for scaling has three characteristicsNumber are ordered (Order)Differences between numbers are ordered (Distance)The number series has a unique origin indicated by the number zero (Origin)

Measurement ScalesNominal No order, or originDetermination of equalityOrdinalOrder but no distance or unique originDetermination of greater or lesser valuesIntervalBoth order and distance but no unique originDetermination of equality of intervals or differencesRatioOrder, distance, and unique originDetermination of equality of ratios

Nominal ScalesPartition a set into categories that are mutually exclusive and collectively exhaustiveCounting is the only arithmetic operationOnly labels and have no quantitative valueNo order or distance relationship and have no arithmetic originNo general used measure of dispersionSeveral tests for statistical significance may be utilizedChi-square testFor measures of association, phi, lambda, or other measure may be appropriate

Ordinal ScalesInclude the characteristics of the nominal scale plus an indicator of orderOrdinal scales are possible if the transitivity postulate is fulfilled.An extension of the ordinal concept occurs when more than one property is of interestAdd and average ranks is technically incorrectUse a multidimensional scaleHave another difficulty when combining the rankings of several respondentsConvert the ordinal scale into an interval scaleThurstones Law of Comparative Judgment

Ordinal ScalesExamples of ordinal scales include opinion and preference scalesPaired -comparison techniquesOrdinal scales have only a rank meaningStatistical measuresCentral tendencymedianDispersionPercentile or quartileCorrelationRank-order methodsStatistical significanceNonparametric methods

Interval ScalesHas the powers of nominal and ordinal plus one additional strengthIncorporates the concept of equality of intervalCalendar time is interval scalesZero time and zero degree(Centigrade and Fahrenheit) are arbitrary originMany attitude scales are presumed to be intervalThurstones differential scale was an early effort to develop such a scaleStatistical measuresCentral tendency (Arithmetic mean)Dispersion (Standard deviation)others (Product moment correlation, t-tests, and F-tests)

Ratio ScalesIncorporate all of the powers of the previous ones plus the provision for absolute zero or originRepresent the actual amounts of a variableExamples are weight, height, distance, and area In behavioral sciences, few situations satisfy the requirement of the ratio scale(Psychophysics offering some exceptions)In business research, we find ratio scale in many areas (money values, population counts, distances)Statistical measuresAll statistical mentioned up to this pointMultiplication and divisionGeometric mean, coefficients of variation

Sources of Measurement DifferencesThe respondent as an error sourceSituation factorsThe measurer as an error sourceInstrument as an error source

Sound MeasurementValidityContent validityCriterion-related validity (Concurrent validity, Predictive validity)Construct validityReliabilityStability (Test-retest)Equivalence (Parallel forms)Internal consistency (Split-half, KR-20, Cronbachs alpha)PracticalityEconomyConvenienceInterpretability

Criteria for Evaluating a Measurement ToolValidityRefer to the extent to which a test measures what we actually wish to measureReliabilityHas to do with the accuracy and precision of a measurement procedurePracticalityIs concerned with a wide range of factors of economy, convenience, and interpretability

ValidityInternal and externalResearch Instrument internal validityMeasure what it is purported to measureDoes the instrument really measure what its designer claims it does?Three major formsContent validityCriterion-related validityConcurrent validityPredictive validityConstruct validity

Content ValidityThe extent to which it provides adequate coverage of the topic under studyDetermination of content validity is judgmental and can be approached in several waysThrough a careful definition of the topicUse a panel of persons to judge

Criteria-Related Validityreflects the success of measures used for prediction or estimationPredict an outcomeEstimate the existence of a current behavior or conditionPredictive and concurrent validity differ in time perspectiveAn opinion questionnaire that correctly forecasts the outcome of a union election has predictive validityAn observational methods that correctly categorizes families by current income class has concurrent validityAny criteria measure must be judged in terms of four qualities: relevance, freedom from bias, reliability, availability

Construct ValidityOne may wish to measure or infer the presence of abstract characteristics for which no empirical validation seems possibleAttitude scalesAptitude testsPersonality testsExampleMeasuring the effects of ceremony on organizational cultureCeremony was operationally defined would have to correspond to an empirically grounded theoryConvergent validityDiscriminant validity

ReliabilityA measure is reliable to the degree that it supplies consistent resultsReliability is a contributor to validity and is a necessary but not sufficient condition for validityReliability is concerned with estimates of the degree to which a measurement is free of random or unstable error

StabilityA measure is said to be stable if you can secure consistent results with repeated measurements of the same person with the same instrumentTest-retest

EquivalenceConsiders how much error may be introduced by different investigators (in observation) or different samples of items being studied (in questioning or scales)Equivalence is concerned with variations at one point in time among observers and samples of itemsInterrater reliability may be used to correlate the observations or scores of the judges and render an index of how consistent their ratings are

Internal ConsistencyUse only one administration of an instrument or test to assess consistency or homogeneity among the itemsSplit-half techniquesSpearman-Brown correction formulaThe test splitting may influence the internal consistency coefficientKuder-Richardson Formula 20Cronbachs Coefficient Alpha

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