A New SEYHAN's Approach in Case of Heterogeneity of Regression Slopes in ANCOVA

Ankarali, Handan Camdeviren/0000-0002-3613-0523; ankarali, seyit/0000-0003-3752-0846WOS: 000432000500006PubMed: 27757767In this study, when the assumptions of linearity and homogeneity of regression slopes of conventional ANCOVA are not met, a new approach named as SEYHAN has been suggested to use conventional ANCOVA instead of robust or nonlinear ANCOVA. The proposed SEYHAN's approach involves transformation of continuous covariate into categorical structure when the relationship between covariate and dependent variable is nonlinear and the regression slopes are not homogenous. A simulated data set was used to explain SEYHAN's approach. In this approach, we performed conventional ANCOVA in each subgroup which is constituted according to knot values and analysis of variance with two-factor model after MARS method was used for categorization of covariate. The first model is a simpler model than the second model that includes interaction term. Since the model with interaction effect has more subjects, the power of test also increases and the existing significant difference is revealed better. We can say that linearity and homogeneity of regression slopes are not problem for data analysis by conventional linear ANCOVA model by helping this approach. It can be used fast and efficiently for the presence of one or more covariates

A Comparison of the Measuring Instruments to Assess Quality of Life in Patients with Fibromyalgia Syndrome

Amaç: Kompleks ve çok boyutlu bir klinik sendrom olan fibromiyalji sendromu (FMS), birçok somatik ve psikolojik yakınmalara neden olduğu için yaşam kalitesini bozmaktadır. Çalışmanın amacı, FMS tanısı almış kişilerin, yaşam kalitesini en kısa sürede ve en verimli şekilde değerlendiren ölçeği belirlemektir. Yanı sıra SF-12, SF-8 ve SF-6D formlarının güvenilirliği ve geçerliliğinin de incelenmesi amaçlandı.Gereç ve Yöntemler: Düzce Üniversitesi Tıp Fakültesi Fiziksel Tıp ve Rehabilitasyon AD'de tanı almış, çalışmaya katılmayı kabul etmiş ve formları tam doldurmuş olan 59 FMS hastası değerlendirildi. Hastaların yaşam kalitesi SF-36, WHOQOL-BREF, QuickDASH, SF-12, SF-8 ve SF-6D ölçekleri ile incelendi. Bulgular: Elde edilen veriler doğrultusunda ölçeklerin iç tutarlılığı ve ölçek puanlarının tekrarlama derecesi yüksek bulundu. SF-36 ölçek puanları ile diğer üç kısa formdan (SF) elde edilen puanlar arasındaki ilişki incelendiğinde, SF-12 ve SF-6D ölçekleri geçerlilik bakımından SF-8'den üstün bulundu. Tartışma ve Sonuç: Geçerlilik için yapılan bütün hesaplamalar değerlendirildiğinde, FMS'de SF12 ve SF-6D ölçekleri yaşam kalitesini ölçmede SF-36 yerine kullanabilir. SF-8'in ise bütün alt boyutlarda SF-12 ve SF-6D kadar etkili olmaması ve mental sağlık alt boyutunun bulunmaması nedenleriyle FMS'de yaşam kalitesini ölçmek amacıyla kullanımı önerilmemektedir.Aim: Fibromyalgia syndrome (FMS), a complex and multidimensional clinical syndrome, disrupts quality of life, causing many somatic and psychological problems. In this study we aimed to determine which measuring instrument should be chosen for the fastest and most efficient assessment of life quality in patients diagnosed with FMS. The reliability and validity of the SF12, SF-8, and SF-6D were also assessed concurrently.Materials and Methods: Fifty-nine patients diagnosed with FMS at Department of Physical Medicine and Rehabilitation, Medical Faculty of Duzce University, who consented to participate in the study and filled out the forms fully were evaluated. Life quality of the patients was investigated by using the instruments SF-36, WHOQOL-BREF, QuickDASH, SF-12, SF-8, and SF-6D.Results: The internal consistency and repeatability of these scales were found to be high in light of the obtained data. When the relation between the SF-36 scores and the scores obtained from the other three short forms (SF) was investigated, the SF-12 and SF-6D scales were found superior to the SF-8 in terms of validity.Discussion and Conclusion: In light of the entire data resulted from our assessment of validity, we suggest that the SF-12 and SF-6D might be preferred over the SF-36 in measuring life quality in patients with FMS. Because its lower efficiency than the SF-12 and SF-6D in all subdimensions and its lack of a mental health-related sub-dimension, the SF-8 is not an appropriate tool for this purpose in FMS

Further Evidence for the Role of Nitric Oxide in Maternal Aggression: Effects of L-NAME on Maternal Aggression towards Female Intruders in Wistar Rats

Ankarali, Seyit/0000-0003-3752-0846; Ankarali, Handan Camdeviren/0000-0002-3613-0523WOS: 000270857000015PubMed: 18657004It has been shown that nitric oxide (NO) increases aggression in male mice, whereas it decreases aggression in lactating female mice and prairie voles. It is also known that aggression can be exhibited at different levels in rodent species, strain or subtypes. The aims of this study were to investigate the proportion of aggressiveness in Wistar rats, the effect of intraperitoneally administered nonspecific nitric oxide synthase (NOS) inhibitor L-NAME (N-G-nitro L-arginine methyl ester) on maternal aggression towards female intruders, and whether these effects are due to NO production or not. Rats were given saline intraperitoneally on the postpartum Day 2 and aggression levels were recorded. The same rats were given 60 mg/kg L-NAME or D-NAME (N-G-nitro D-arginine methyl ester) on the postpartum Day 3 and their effects on aggression levels were compared to saline. While L-NAME administration did not cause any differences in the total number of aggressive behavior, aggression duration and aggression intensity, it reduced the proportion of animals showing aggressive behavior. In addition, the latency of the first aggression was significantly increased by L-NAME. In the D-NAME group, however, no significant change was found. Our results have shown that L-NAME reduces maternal aggression towards female intruders in Wistar rats through inhibition of NO production. These results suggest that the role of NO in offensive and defensive maternal aggression shares neural mechanisms

A Bootstrap Confidence Interval for Skewness and Kurtosis and Properties of t-test in Small Samples from Normal Distribution

11th National Congress of Biostatistics -- MAY 27-30, 2008 -- Malatya, TURKEYAnkarali, Handan Camdeviren/0000-0002-3613-0523; Ankarali, Seyit/0000-0003-3752-0846WOS: 000272760100003Objectives: We examined the test properties about mean and mean differences, sampling distributions properties of mean and standard deviation, especially when the sample size is lower than 10 and the variable has normal distribution in population. In addition, we aimed to construct a 95% bootstrap confidence interval for skewness and kurtosis values in various samples sizes. Materials and Methods: In our simulation study, 10,000 samples with replacement were taken from the standard normal population Various sample sizes were evaluated Data which were obtained from an animal study were used for comparison of t-test's and Wilcoxon sign test's power in small sample. Results: According to our results, sampling distribution of skewness coefficients has normal distribution, however, kurtosis coefficients have positively skewed distribution. A bootstrap confidence interval for these coefficients by using these sampling distribution can be used for normality test Moreover, it was shown that test statistic for the mean has t-distribution in all studied sample sizes Conclusion: We can say that distribution shape of the variable plays a more important role than sample size in selection of appropriate test statisti

Normal dağılımdan alınan küçük örneklerde çarpıklık ve basıklık için bootstrap güven aralığı ve t-testinin özellikleri

Amaç: Normal dağılımdan alınmış ve özellikle örnek genişliği 10'dan küçük olan örneklerden hesaplanan ortalama ve standart sapmanın örnekleme dağılımları ve ortalamaya ait hipotez testinin özellikleri incelenerek yine bu örneklerde çarpıklık ve basıklık katsayılarına ait %95 ihtimalli bootstrap güven aralıklarının oluşturulması amaçlanmıştır. Gereçler ve Yöntemler: Yapılan simülasyon çalışmasında standart normal dağılım gösteren popülasyondan geri iadeli olarak 10 000 örnek alınmıştır. Farklı örnek genişlikleri incelenmiştir. Küçük örnekte Wilcoxon işaret testi ve t-testinin güçlerini karşılaştırmalı olarak göstermek için bir hayvan deneyinden alınan veriler kullanılmıştır. Bulgular: Elde edilen bulgular değerlendirildiğinde, çarpıklık katsayısının örnekleme dağılımı normal dağılım olarak bulunurken, basıklık katsayısının pozitif çarpık bir dağılımı olduğu görülmüştür. Bu katsayıların örnekleme dağılımları kullanılarak bulunan bootstrap güven aralığı verilerin normallik testinde kullanılabilir. Bunun ötesinde örnek genişliklerinin tamamında ortalamaya ait test istatistiğinin t-dağılımına sahip olduğu görülmüştür. Sonuç: Uygun test istatistiğinin seçiminde verilerin dağılım şeklinin, örnek genişliğine göre daha önemli role sahip olduğu söylenebilir.Objectives: We examined the test properties about mean and mean differences, sampling distributions properties of mean and standard deviation, especially when the sample size is lower than 10 and the variable has normal distribution in population. In addition, we aimed to construct a 95% bootstrap confidence interval for skewness and kurtosis values in various samples sizes. Materials and Methods: In our simulation study, 10,000 samples with replacement were taken from the standard normal population. Various sample sizes were evaluated. Data which were obtained from an animal study were used for comparison of t-test's and Wilcoxon sign test's power in small sample. Results: According to our results, sampling distribution of skewness coefficients has normal distribution; however, kurtosis coefficients have positively skewed distribution. A bootstrap confidence interval for these coefficients by using these sampling distribution can be used for normality test. Moreover, it was shown that test statistic for the mean has t-distribution in all studied sample sizes. Conclusion: We can say that distribution shape of the variable plays a more important role than sample size in selection of appropriate test statistic