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Follow-Up Of Fisher F Test With Significantly Low Values In Small Samples


  • Alina BARBU

    () (Bucharest Academy of Economic Studies, Romania)


Fisher’s F-test, a common statistical choice for testing differences between groups, has been found to return unusually small, significant values. This paper presents a follow-up of two examples from medical surveys which registered significantly low F-values when testing for differences between evaluations (marks) given by physicians in different specialties. A new wave of the two surveys has been conducted, but did not register low F-ratios. The datasets of the two waves are compared for specific traits which may have caused the low F-ratios in the original wave. Results confirmed some of the previous findings (e.g. normality should always be tested because non-normal data may “hide” behind normal F-ratios), but showed similar conditions of sample size, non-normality of data and influence of a second variable (locality). The main conclusion of the follow-up is that neither of these causes, alone or acting together, guarantees that significantly low F-ratios will occur. This makes generalisation, or preventing low F-ratios, a difficult, if not impossible task.

Suggested Citation

  • Alina BARBU, 2011. "Follow-Up Of Fisher F Test With Significantly Low Values In Small Samples," Journal of Doctoral Research in Economics, The Bucharest University of Economic Studies, vol. 3(2), pages 41-48, June.
  • Handle: RePEc:aes:jdreco:v:3:y:2011:i:2:p:41-48

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    More about this item


    Fisher’s F-test; significantly low F-ratio; medical marketing research; non-normality;

    JEL classification:

    • C12 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Hypothesis Testing: General
    • C18 - Mathematical and Quantitative Methods - - Econometric and Statistical Methods and Methodology: General - - - Methodolical Issues: General


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