1、Chapter 9Scaling,Reliability and ValidityChapter Objectives Know how and when to use the different forms of rating scales and ranking scales Explain stability and consistency,and how they are established Explain the different forms of validity Discuss what goodness of measures means,and why it is ne
2、cessary to establish it in research Rating and Ranking Scales Rating Scales have several response categories and are used to elicit responses with regard to the object,event or person studied.Ranking Scales make comparisons between or among objects,events or persons,and elicit the preferred choices
3、and ranking among them.Rating Scales dichotomous scale category scale Likert scale numerical scales semantic differential scale itemised rating scale fixed or constant sum rating scale Stapel scale graphic rating scale consensus scale Dichotomous ScaleUsed to elicit a Yes or No answer,eg:Do you own
4、a car?YesNoCategory ScalesQualityExcellentGoodFairPoorImportanceVeryimportantFairlyimportantNeutralNot soimportantNot at allimportantInterestVeryinterestedSomewhatinterestedNot veryinterestedFrequencyAll of the timeVery oftenOftenSometimesHardly everSource:Zikmund(2000:292)Likert ScaleIndicate the e
5、xtent to which you agree or disagree with the following statements:My work is very interesting 1 2 3 4 5Life without my work would be dull 1 2 3 4 5Strongly disagree Disagree Neither agree nor disagree Agree Strong agree 1 2 3 4 5 Semantic Differential ScaleBadGoodUnresponsiveResponsiveTimidCourageo
6、usNumerical ScaleHow pleased are you with your new car?Extremely Extremelypleased 7 6 5 4 3 2 1 displeasedItemised Rating ScaleThis is an unbalanced rating scale which does not have a neutral point.Not at allinterestedSomewhatinterestedModeratelyinterestedVery muchinterested1234How would you rate yo
7、ur interest in changingcurrent organisational policies?1234Fixed or Constant Sum Rating ScaleRespondents are asked to distribute a given number of points across various items,eg:FragranceColourShapeSizeTexture of latherTotal points 100Stapel ScaleMeasures the direction and intensity of the attitude
8、towards the items under study,eg+3+3+3+2+2+2+1+1+1Adopting moderntechnologyProduct innovationInterpersonal skills111222333Graphic Rating ScaleRanking Scales paired comparison forced choice comparative scalePaired Comparison Used when,among a small number of objects,respondents are asked to choose be
9、tween two objects at a time.The paired choices for n objects will be(n)(n-1)/2).Forced ChoiceRank your preferences among the following magazines,1 being your preferred choice and 5 being your least preferred:Australian Financial Review_Business Review Weekly_Playboy_The Economist_Time_Comparative Sc
10、aleIn a volatile financial environment,compared with shares,how useful is it to invest in government bonds?More useful About the same Less useful 1 2 3 4 5Goodness of Measures Reliability measures How stable and consistent is the measuring instrument?Validity measures Are we measuring the right thin
11、g?Reliability and Validity in Target ShootingForms of Reliability and ValidityReliability Stability refers to the ability of a measure to maintain stability over time,despite uncontrollable testing conditions or the state of the respondents themselves Internal consistency indicates how well the item
12、s hang together as a set and can independently measure the same concept,so respondents attach the same overall meaning to each of the items Stability of Measures Test-retest reliability the reliability coefficient obtained with a repetition of the same measure on a second occasion Parallel-form reli
13、ability the correlation obtained from responses on two comparable sets of measures(changed for wording&question order)tapping the same constructInternal Consistency of Measures Inter-item consistency reliability test of the consistency of respondents answers to all the items in a measure usually tested by Cronbachs coefficient alpha Split-half reliability reflects the correlations between two halves of an instrument Types of Validity
