1

Measurement and Data CollectionMeasurement and Data Collection

What and How?What and How? Types of ScalesTypes of Scales

NominalNominalOrdinalOrdinalIntervalIntervalRatioRatio

2ReliabilityReliability

““Does the instrument provide us Does the instrument provide us

with with consistentconsistent assessments?” assessments?”

3ReliabilityReliability

• TheoryTheory

•XXTotalTotal = X = XTrueTrue + X + XErrorError

•VVTotalTotal = V = VTrueTrue + V + VErrorError

• Reliability = Reliability = VVTrueTrue

VVTotalTotal

4 •ReliabilityReliability

TheoryTheory

rr1122

TrueTrue = = ReliabilityReliability

““Proportion of variance in scores that Proportion of variance in scores that can be considered ‘true’ variance”can be considered ‘true’ variance”

5 •ReliabilityReliability

• Types of ReliabilityTypes of Reliability

• Internal consistencyInternal consistency

• StabilityStability

6

ReliabilityReliability

Reliability coefficientReliability coefficientParallel formParallel formTest-retestTest-retestSplit-HalfSplit-HalfKuder-RichardsonKuder-RichardsonCronbach’s AlphaCronbach’s Alpha

See page 300, Table12.1See page 300, Table12.1

7ReliabilityReliability

• Sources of ErrorSources of Error

• Inadequate sampling of itemsInadequate sampling of items• Cronbach’s alpha internal Cronbach’s alpha internal

consistency reliabilityconsistency reliability

• Different occasionsDifferent occasions• Stability reliabilityStability reliability

8ValidityValidity

ContentContent

Criterion-relatedCriterion-related

PredictivePredictive ConcurrentConcurrent

Construct-relatedConstruct-related

9Tests and MeasuresTests and Measures

Standardized Standardized (normative vs criterion)(normative vs criterion)

Buros Mental Measurements YearbookBuros Mental Measurements Yearbook

Tests in PrintTests in Print

10Types of MeasuresTypes of Measures

Attitude MeasuresAttitude MeasuresLikertLikertSematic DifferentialSematic Differential

Aptitude TestsAptitude Tests Personality MeasuresPersonality Measures

ProjectiveProjectiveNon-projectiveNon-projective

11Types of MeasuresTypes of Measures

Observation SystemsObservation Systems

Wholistic ScoringWholistic Scoring

12Scoring and Data PreparationScoring and Data Preparation

Codebook Codebook (Codebook.doc)(Codebook.doc)

Coding Information (scaling)Coding Information (scaling)(Gatekeeper Final Data.(Gatekeeper Final Data.xlsxls))