Presentation on theme: "Index and Scales Review – What is a concept? What are indicators? Universe of meaning– possible meaning of concepts. Could have broad or narrow universe."— Presentation transcript:
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?
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.
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.
Index Summary 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
Do you favor mandatory coercive measures to correct community problems. a)Mandatory employee drug testing b)Drug testing for high school athletes c)Mandatory seat belt use d)Ban on new shopping center Response: Favor=1 and Oppose=0.
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 Scales Likert Scale
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
Likert Scale measuring Self Esteem Please check the single response option following each statement that most closely reflects your judgement. 1.I feel I have a 2. I feel I do not have a number of good much to be proud of qualities ___ Almost always true __ Almost always true ___ Often true __ Often true ___ Sometimes true __ Sometimes true ___ Seldom true __ Seldom true ___ Almost never true
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.
Group Exercise Try building a Likert Scale to test how serious college students are about their education.
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 meaning 2) Potency (P) denoting “weak-strong” dimension 3) Activity (A), signifying an “active-passive” continuum of meaning.
Guttman Scale Based 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.
Suppose you are studying worker alienation in a factory and the indicators of alienation are: a) Signing a recent petition against new work rules b) Calling in sick a lot c) Having filed a grievance against management in the past year.
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 types Mixed Types
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.