, Volume 16, Issue 2, pp 167–188

Time-limit tests: Estimating their reliability and degree of speeding


  • Lee J. Cronbach
    • University of Illinois
  • W. G. Warrington
    • University of Illinois

DOI: 10.1007/BF02289113

Cite this article as:
Cronbach, L.J. & Warrington, W.G. Psychometrika (1951) 16: 167. doi:10.1007/BF02289113


Non-spurious methods are needed for estimating the coefficient of equivalence for speeded tests from single-trial data. Spuriousness in a split-half estimate depends on three conditions; the split-half method may be used if any of these is demonstrated to be absent. A lower-bounds formula,rc, is developed. An empirical trial of this coefficient and other bounds proposed by Gulliksen demonstrates that, for moderately speeded tests, the coefficient of equivalence can be determined approximately from single-trial data. It is proposed that the degree to which tests are speeded be investigated explicitly, and an indexτ is advanced to define this concept.

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© Psychometric Society 1951