MEASUREMENT OF VARIABLES: OPERATIONAL DEFINITION AND SCALESCHAPTER 8

HOW VARIABLES ARE MEASURED?Two types of variables:Variable that lends itself to objective and precise measurementVariable that doesnt lend itself to accurate measurement because of its subjective nature. Abstract notions observable characteristic behavior measurable in a tangible way called operationalizing the concepts Operational definition is a statement of the specific dimensions and elements through which a concept will become measurable

OPERATIONAL DEFINITION: DIMENSIONS AND ELEMENTS

OPERATIONAL DEFINITION: DIMENSIONS AND ELEMENTS

SCALESNominal Scales: splits data into groups, e.g., men, womenOrdinal Scales: ranks data in some order, e.g., exercising for 20 minutes is good, for 30 minutes is better, for 40 minutes is bestInterval Scales: sets data on a continuum, e.g.12345very lowvery highRatio Scales: starts with absolute zero and indicates proportion, e.g.0510ten is twice as big as five

MEASUREMENT: SCALING, RELIABILITY, VALIDITYCHAPTER 9

SCALING TECHNIQUES:1. Rating ScalesRating ScalesDichotomous Scales yes or no answerCategory Scales uses multiple items to elicit a single response Likert Scales to examine how strongly subjects agree or disagree with statement on a 5-point scale Semantic Differential Scales several bipolar attributes are identified at the extremes of the scaleNumerical Scales similar with Semantic Differential Scales with number on 5 or 7 point scale are provided

SCALING TECHNIQUES:1. Rating ScalescontItemized Rating Scales a 5 or 7 point scale with anchors is provided for each item and the respondent state the appropriate number on the side of each item Fixed or Constant Sum Rating Scales the respondents are asked to distribute a given number of points across various items, the sum is constantStapel Scales measure both direction and intensity of the attitude toward the item under studyGraphic Rating Scales placing a mark at the appropriate point on the line

SCALING TECHNIQUES2. Ranking ScalesRanking Scales Paired Comparisons used when, among small number of objects, respondents are asked to choose between two objects at a time.Forced Choice enables respondents to rank objects relative to one another, among alternatives provided.Comparative Scales provides a benchmark or a point of reference to assess attitude toward the current object, event, or situation under study.

GOODNESS OF MEASURESStabilityTest-retest reliabilityParallel-form reliabilityInternal ConsistencySplit-half reliabilityInteritem consistency reliabilityValidityContent ValidityFace validityCriterion-Related ValidityConcurrent validityPredictive validityConstruct Validity