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The modified Mood test for the scale alternative and its numerical comparisons
Hidetoshi Murakami,하형태 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.4
On statistical hypotheses testing in two-sample problems, the Mood test is popular as one of the most efficient nonparametric tests for dispersion differences. In this paper, we show that a modification of the Mood test proposed by Tamura (1963) can gain even more efficiency and power under various distributional assumptions. The accuracy of the proposed approximations to the tail probabilities and critical values of the modified Mood test, namely Mp, were investigated. Our results showed that the Edgeworth expansion was more accurate than the other approximations. Asymptotic efficiencies and the optimal value p of the modified Mood test under various distributional assumptions were examined, with the results revealing that the large (small) value of p was useful for light (heavy) tail distributions. Additionally, the power of the modified Mood test for the one-sided alternative with various population distributions for small sample sizes was investigated via Monte Carlo simulations. Finally, the proposed method was demonstrated using real data.
Prepulse Inhibition of Startle Response: Recent Advances in Human Studies of Psychiatric Disease
Hidetoshi Takahashi,Ryota Hashimoto,Masao Iwase,Ryouhei Ishii,Yoko Kamio,Masatoshi Takeda 대한정신약물학회 2011 CLINICAL PSYCHOPHARMACOLOGY AND NEUROSCIENCE Vol.9 No.3
Prepulse inhibition (PPI) is considered to be one of the most promising neurophysiological indexes for translational research in psychiatry. Impairment of PPI has been reported in several psychiatric diseases, particularly schizophrenia, where PPI is considered a candidate intermediate phenotype (endophenotype) of the disease. Recent findings from a variety of research areas have provided important evidence regarding PPI impairment. Human brain imaging studies have demonstrated the involvement of the striatum, hippocampus, thalamus and frontal and parietal cortical regions in PPI. In addition, several genetic polymorphisms,including variations in the genes coding for Catechol O-methyltransferase, Neuregulin 1, nuclear factor kappa-B subunit 3 and serotonin-2A receptor were related to PPI; and these findings support PPI as a polygenetic trait that involves several neurotransmitter pathways. Early psychosis studies suggest that PPI disruption is present before the onset of psychosis. Also, discrepancy of PPI impairment between children and adults can be found in other psychiatric diseases, such as autistic spectrum disorders and posttraumatic stress disorder, and comprehensive investigation of startle response might contribute to understand the impairment of the neural circuitry in psychiatric diseases. Finally, recent studies with both Asian and Caucasian subjects indicate that patients with schizophrenia exhibit impaired PPI, and impaired sensorimotor gating might be a global common psychophysiological feature of schizophrenia. In conclusion, studies of PPI have successfully contributed to a better understanding of the fundamental neural mechanisms underlying sensorimotor gating and will certainly be most valuable in devising future approaches that aim to investigate the complex pathogenesis of psychiatric diseases.
Unbiasedness and biasedness of the Jonckheere–Terpstra and the Kruskal–Wallis tests
Hidetoshi Murakami,이성건 한국통계학회 2015 Journal of the Korean Statistical Society Vol.44 No.3
Finding the unbiasedness and biasedness of test statistics is important in testing a hypothesis. In this study, the unbiasedness/biasedness of the Jonckheere–Terpstra test is investigated for ordered alternatives. Our results show that the one-sided Jonckheere–Terpstra test is unbiased for the location parameter family of distributions and that the nonrandomized two-sided Jonckheere–Terpstra test is biased for the shifted location parameter. Additionally, the unbiasedness/biasedness of the Kruskal–Wallis test is considered for the general two-sided alternatives. By giving a counter example, our investigation reveals that the Kruskal–Wallis test is biased against a shifted location parameter for unequal sample sizes. Our results indicate that we require to consider a bias correction for the nonparametric tests.
A simplified PCR assay for fast and easy mycoplasma mastitis screening in dairy cattle
Hidetoshi Higuchi,Hidetomo Iwano,Kazuhiro Kawai,Takehiro Ohta,Tetsu Obayashi,Kazuhiko Hirose,Nobuhiko Ito,Hiroshi Yokota,Yutaka Tamura,Hajime Nagahata 대한수의학회 2011 Journal of Veterinary Science Vol.12 No.2
A simplified polymerase chain reaction (PCR) assay was developed for fast and easy screening of mycoplasma mastitis in dairy cattle. Species of major mycoplasma strains [Mycoplasma (M.) bovis, M. arginini, M. bovigenitalium, M. californicum, M. bovirhinis, M. alkalescens and M. canadense] in cultured milk samples were detected by this simplified PCR-based method as well as a standard PCR technique. The minimum concentration limit for detecting mycoplasma by the simplified PCR was estimated to be about 2.5 × 10^3 cfu/mL and was similar to that of the standard PCR. We compared the specificity and sensitivity of the simplified PCR to those of a culture method. Out of 1,685 milk samples cultured in mycoplasma broth, the simplified PCR detected Mycoplasma DNA in 152 that were also positive according to the culture assay. The sensitivity and specificity of the simplified PCR were 98.7% and 99.7%, respectively, for detecting mycoplasma in those cultures. The results obtained by the simplified PCR were consistent with ones from standard PCR. This newly developed simplified PCR, which does not require DNA purification, can analyze about 300 cultured samples within 3 h. The results from our study suggest that the simplified PCR can be used for mycoplasma mastitis screening in large-scale dairy farms.