1. 

   Edward Smith Active Member

   Why is the correct test statistic here (A-E)^2 / E, rather than z?

    

   Edward Smith, Sep 15, 2021

   #1
2. 

   Dave Johnson ActEd Tutor Staff Member

   Hi Edward
   
   z is defined as:
   
   z = (A - E) / sqrt(E)
   
   ie the individual standardised deviations.
   
   The chi-squared test statistic is sum(z^2). Substituting in the formula for z, we get:
   
   z^2 = (A - E)^2 / E
   
   which is the corrected test statistic given in the Examiner's Report.
   
   Hope that helps
   
   Dave

    

   Dave Johnson, Sep 16, 2021

   #2

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