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Following my earlier question here, is there a quick way (using Excel or SPSS) to ascertain/calculate the reliability of composite scores.

Reliability in this case is for me to say confidently (i.e. the ordinary not statistical meaning of this word!) that the composite score is consistently measuring the concept.

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Adhesh Josh
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  • "that the composite score reflects the concept it is measuring" That is much closer to _validity_ then to _reliability_. Perhaps you ought to rename/retag your question. – ttnphns Oct 05 '11 at 13:24

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A few quick points:

  • If the component tests are assumed to reflect a common underlying concept, then internal consistency measures are often reported; e.g., Cronbach's alpha.
  • If this is not the case, you could administer the measures used to derive the composite twice, and calculate a test-retest reliability.
  • You might also want to read up on the literature related to formative measures: e.g., "reliability of formative measures" on google scholar
Jeromy Anglim
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