The Chi-square is a statistic, which is traditionally used in disproportionality analyses. In certain standard queries of the EudraVigilance Data Analysis System, the Chi-square is used as an alternative measure of association between the medicinal product P and the adverse event R based on the following calculation:
χ2 =(AD−BC)2 (A+B+C+D)/[(A+B)(C+D)(A+C)(B+D)]
χ2 ≥ 4 is indicator of considering signal.
- The value A indicates the number of individual cases with the suspect medicinal product P involving an adverse event R.
- The value B indicates the number of individual cases related to the suspect medicinal product P, involving any other adverse events but R.
- The value C indicates the number of individual cases involving event R in relation to any other medicinal products but P.
- The value D indicates the number of individual cases involving any other adverse events but R and any other medicinal products but P.
