Validating scales and indexes

02 Mar

The word scale is sometimes (including in academic literature) used to refer to another composite measure, that of an index. With comparative scaling, the items are directly compared with each other (example: Do you prefer Pepsi or Coke? In noncomparative scaling each item is scaled independently of the others (example: How do you feel about Coke? Composite measures of variables are created by combining two or more separate empirical indicators into a single measure.Composite measures measure complex concepts more adequately than single indicators, extend the range of scores available and are more efficient at handling multiple items.Content validation (also called face validity) checks how well the scale measures what is supposed to measured.

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Alternative forms reliability checks how similar the results are if the research is repeated using different forms of the scale.Both the initial items and reference scales were translated into seven languages and completed via Internet by participants (N = 4,052) aged 16 to 60 years from nine countries (Germany, India, Japan, Mexico, Russia, Spain, Sweden, Turkey, and USA).Results from this initial validation study provided very good support for the psychometric properties of the PHI (i.e., internal consistency, a single-factor structure, and convergent and incremental validity).In addition to scales, there are two other types of composite measures.Indexes are similar to scales except multiple indicators of a variable are combined into a single measure.