PubMed · 15889579
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B Norsa'adah. 2004. Wrong conclusion when the statistical test is incorrect.. https://pubmed.ncbi.nlm.nih.gov/15889579/
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The aim of this article was to derive an approximation of the distribution of Pearson's statistic for 2 x m contingency tables to calculate power for case-control studies accurately and efficiently in terms of computer time. We first prove that, rather than a non-central chi-square distribution, Pearson's statistic is asymptotically equivalent with the sum of squares of m independent normal random variables whose variances are typically different under the alternative hypothesis. Based on this asymptotically equivalent (AE) we derive a cost-effective approximation (CE). Numerical results show that CE was almost as precise as AE, but computationally more efficient. Although somewhat less costly in terms of CPU time, we show that a commonly used approximation using the non-central chi-square distribution can be very inaccurate and overestimate power in some scenarios and underestimate it in others. Simulations and exact distributions, on the other hand, are accurate but computationally very intensive compared to our CE. The CE reached its lowest accuracy under the null hypothesis where it has a chi-square distribution with m - 1 degree of freedom. This suggests that CE can be used to calculate power for tables where researchers would feel comfortable using Pearson's chi-square test.
This is the first study of a possible molecular genetic basis for schizophrenia with obsessive-compulsive disorder (OCD). We performed a case-control association study of the catechol-O-methyltransferase (COMT) Val158Met polymorphism in schizophrenia-OCD patients, OCD and healthy controls. One hundred and thirteen schizophrenia-OCD patients, 79 OCD patients and 171 control subjects were genotyped for the Val(158)Met polymorphism in the COMT gene. There was no significant difference in allele and genotype distribution of the COMT gene between schizophrenia-OCD patients and healthy controls. The low-activity Met allele and Met/Met genotype were more frequent in OCD men than in schizophrenia-OCD and control individuals. This difference, however, was not statistically significant following correction for multiple comparisons. These results do not support the hypothesis that the COMT Val158Met gene polymorphism is associated with liability to schizophrenia-OCD.
Hepatitis C virus (HCV) infection is associated with chronic hepatitis, cirrhosis, and hepatocellular carcinoma. Recent evidences have also suggested that HCV infection contributes to development of autoimmune disorders and B-cell nonHodgkin's lymphoma (NHL). Mechanisms by which HCV infection promotes B-cell NHL development remain unclear. Increased serum osteopontin (OPN) levels have been associated with several autoimmune diseases as well as a variety of cancers. However, the association between OPN and B-cell NHL or HCV-associated B-cell proliferation has not previously been reported. In the present study, we determined whether serum OPN differences were associated with HCV infection, type II mixed cryglobulinemia (MC) syndrome and B-cell NHL. Serum OPN levels were measured by capture enzyme-linked immunosorbent assay. Our results show that high serum OPN levels are associated with B-cell NHL and HCV infection. Interestingly, highest serum OPN concentrations were found among HCV-infected patients with concomitant type II MC syndrome with and without B-cell NHL. These data indicate that OPN is involved in the lymphomagenesis, especially, in the context of HCV infection and autoimmune diseases.