Presentation on theme: "Index and Scales Review – What is a concept? What are indicators?"— Presentation transcript:
1 Index and Scales Review – What is a concept? What are indicators? Universe of meaning– possible meaning of concepts. Could have broad or narrow universe.Why use several indicators to capture the universe of a concept?
2 Particular element of meaning may be inadequate. One indicator may not measure the aspect of the concept well.Ideal for establishing reliability through use of parallel forms.
3 Importance of composite measures It is not easy to devise single questions to capture the complexities of certain concepts.Indexes and scales reduce complex information to a single easy to understand score while maintaining the specific details of all individual indicators.
4 IndexSummary measure of a complex concept obtained by adding up values of the indicators used to measure the concept’s universe of meaning.Summated index – index made up of two indicators that have values: 1. Yes/agree and 0. No/disagree
5 Do you favor mandatory coercive measures to correct community problems. Mandatory employee drug testingDrug testing for high school athletesMandatory seat belt useBan on new shopping centerResponse: Favor=1 and Oppose=0.
6 Complex Scales· Scales are critical in showing intensity structures among the indicators. The items going into a composite measure may have different intensities in terms of the variable.Types of ScalesLikert Scale
7 Types of Scales Likert Scale Consists of series of positive and negative opinion statements concerning a construct, each accompanied by a five- or seven point response scale
8 Likert Scale measuring Self Esteem Please check the single response option following each statement that most closely reflects your judgement.I feel I have a I feel I do not havea number of good much to be proud ofqualities___ Almost always true __ Almost always true___ Often true __ Often true___ Sometimes true __ Sometimes true___ Seldom true __ Seldom true___ Almost never true ___ Almost never true
9 Scoring – score almost always true 5 and reverse the scoring on the second question. Note that the first item is positively worded and the second item is negatively worded.
10 Group ExerciseTry building a Likert Scale to test how serious college students are about their education.
11 Semantic Differential Scale Measure the multifaceted meaning of constructs.Meaning of any concept can be represented as a point in semantic space formed by three dimensions:1) Evaluation (E), represents a “good-bad” continuum of meaning2) Potency (P) denoting “weak-strong” dimension3) Activity (A), signifying an “active-passive” continuum of meaning.
13 Guttman ScaleBased on the fact that some items under consideration may prove to be more extreme indicators of the variable than others.Anyone who gives a strong indicator of some variable will also give the weaker indicators.
14 Suppose you are studying worker alienation in a factory and the indicators of alienation are: a) Signing a recent petition against newwork rulesb) Calling in sick a lotc) Having filed a grievance againstmanagement in the past year.
15 EXAMPLE.Table 1 below tests the assumptionthat those who have filed a grievance are likely to choose the first two.Sign petition Called sick Grievance No.Scale typesMixed Types
16 The Coefficient of reproducibility (CR) tests how closely any set of index data reproduces a perfect scale.CR= 1 – (No. errors / No. of entries)A coefficient of reproducibility of 0.90 or greater is accepted as a significant approximation of a perfect scale.