Presentation on theme: "Index and Scales Review – What is a concept? What are indicators?"— Presentation transcript:
1Index 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?
2Particular 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.
3Importance 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.
4IndexSummary 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
5Do 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.
6Complex 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
7Types 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
8Likert 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
9Scoring – 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.
10Group ExerciseTry building a Likert Scale to test how serious college students are about their education.
11Semantic 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.
13Guttman 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.
14Suppose 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.
15EXAMPLE.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
16The 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.