Testing for suspected impairments and dissociations in single-case studies in neuropsychology: evaluation of alternatives using monte carlo simulations and revised tests for dissociations

Neuropsychology. 2005 May;19(3):318-31. doi: 10.1037/0894-4105.19.3.318.


In neuropsychological single-case studies, a patient is compared with a small control sample. Methods of testing for a deficit on Task X, or a significant difference between Tasks X and Y, either treat the control sample statistics as parameters (using z and zD) or use modified t tests. Monte Carlo simulations demonstrated that if z is used to test for a deficit, the Type I error rate is high for small control samples, whereas control of the error rate is essentially perfect for a modified t test. Simulations on tests for differences revealed that error rates were very high for zD. A new method of testing for a difference (the revised standardized difference test) achieved good control of the error rate, even with very small sample sizes. A computer program that implements this new test (and applies criteria to test for classical and strong dissociations) is made available.

Publication types

  • Comparative Study

MeSH terms

  • Computer Simulation
  • Dissociative Disorders / physiopathology*
  • Evaluation Studies as Topic
  • Humans
  • Monte Carlo Method*
  • Neuropsychology*
  • Sample Size
  • Single Person*