Yazar "Yeşilova, Abdullah" seçeneğine göre listele

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  • Küçük Resim
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    The Application of Overdispersion and Generalized Estimating Equations in Repeated Categorical Data Related to The Sexual Behaviours Traits of Farm Animals
    (Journal of Applied Sciences, 2007) Yeşilova, Abdullah; Yılmaz, Ayhan
    In this study, the poison regression, negative binomial regression and generalized estimating equations were applied to the repeated measurements based on count data obtained from the sexual behaviours of ram lambs. Negative binomial regression was more effective to handle the overdispersion that causes bias in parameter estimations in Poison regression. The generalized estimating equations were used for analyzing repeated categorical data. GEE estimates were obtained by using the exchangeable working correlation. As a result of GEE analyses, it was concluded that flehmen lip curl response, tail raising, mount duration, vocalization and weight of the ram lamb were statistically important (p<0.05) for mount frequent. However, the anogenital sniff found be not significant.
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    Comparing covariance structures using different optimization techniques in GLMM on some sexual behaviors of male lambs
    (The Journal of Animal & Plant Sciences, 2013) Ser, Gazel; Yeşilova, Abdullah; Yılmaz, Ayhan
    This study is concerned with use of generalized linear mixed models (GLMM) to analyse the repeated measurements based on count data obtained from the sexual behaviors of male lambs. A combination of different optimization techniques and covariance structures were applied to four constructed models. These models were defined in terms of random effect specifications. Therefore, residuals was assumed to be random (Model A), intercept assumed to be random effect (Model B), time (slope) assumed to be random effect (Model C) and both intercept and time assumed to be random effects (Model D). Five different techniques quasi-newton (QUANEW), newton-raphson NEWRAP), trust region (TRUREG), newton-raphson ridge (NRRIDG) and double-dogleg (DBLDOG) optimization techniques were used for analyzing these models. Three different covariance structures compound symmetry (CS), unstructured (UN) and firstorder autoregressive (AR(1)) were used. In conclusion, based on likelihood criteria, the Model A with CS structure outperformed other models for the repeated measurement data of sexual behavior characteristics.
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    Öğe
    Modeling insect-egg data with excess zeros using zero-inflatedregression models.Hacettepe Journal of Mathematics and Statistics. 39(2): 273-282
    (2010) Yeşilova, Abdullah; Kaydan, Bora; Kaya, Yılmaz
    As zero-inflated observations occur very often in studies on plant pro?tection, models taking into account zero-inflated observations are fre?quently required. Especially, zero-inflated observations occur in large numbers for insects whose post-oviposition period lasts long, or that generally lay their eggs during the first days of the oviposition period. For the data used in this study, 1114 (43.84%) of the 2541 observations were zero. In the selection of an appropriate regression model, zero?inflated negative binomial regression was chosen as the best model. In all regression models, the day of laying and the three different hosts were seen to have a significant effect on daily egg numbers (p < 0.01).
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    Modeling with Gaussian mixture regression for lactation milk yield in Anatolian buffaloes
    (Indian Jornal Animal Research, 2016) Yeşilova, Abdullah; Yılmaz, Ayhan; Ser, Gazel; Kaki, Barış
    The purpose of this study was to classify Anatolian buffalo using Gaussian mixture regression model according to discrete and continuous environmental effects. Gaussian mixture model performs separately regression analysis both within and between groups. This is an important property of Gaussian mixture models which makes it different from other multivariate statistical methods. The data were obtained from 1455 Anatolian buffalo lactation milk yield records reared in seven different locations in Bitlis province, Turkey. Age of dam, lactation duration and locations were considered as environmental effects on lactation milk yield. Data set was divided into three homogenous subgroups with respect to AIC and BIC in the Gaussian mixture regression, based on environmental effects on lactation milk yield. Estimated mean for lactation milk yields and mixing probabilities for the first, second and third subgroups were determined as 1494.33 kg (16.9%), 540.33 kg (45.2%) and 847.61 (37.9%), respectively. The numbers of buffalo in each subgroup according to mixing probability were obtained as 159, 756, and 540 for the first, second, and third groups, respectively. The effects of lactation period, age of dam and villages were found statistically significant on lactation milk yield in subgroup 1 that was highest mean for lactation milk yield (p<0.01). In conclusion, results showed that Gaussian mixture regression was an important tool for classifying quantitative traits considering environmental effects in animal breeding.
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    Norduz ve Karakas Koçlarında Eseysel Davranıs Özellikleri ve Yasla Değisimi
    (TARIM BİLİMLERİ DERGİSİ, 2009) Yılmaz, Ayhan; Karakuş, Ferda; Yeşilova, Abdullah
    Bu çalışma, Akkaraman varyetesi Norduz ve Karakaş koçlarında eşeysel davranış özelliklerinin yasa göre değişimini belirlemek amacıyla yapılmıştır. Bu amaçla koçlar, yaslarına göre iki gruba ayrılmış; birinci ve ikinci grubu sırasıyla 3? ve 2 yaslı koçlar oluşturmuştur. Eşeysel davranışların belirlenmesi için birinci (n=7) ve ikinci grup (n=5) koçlar bireysel olarak 2 günde bir 15 dakika süreyle 3-5 kızgın koyunla test edilmiştir. Çalışmada incelenen davranış özelliklerinden flehmensiz genital organları koklama (FSGOK), flehmenli genital organları koklama (FGOK), kuyruk kaldırma (KK), ses çıkarma (SÇ), ejakulasyonsuz (EJSBS) ve ejakulasyonlu binis sayısına (EJBS) ilişkin ortalama değerler sırasıyla; 4.65±0.53, 2.08±0.19, 8.58±0.97, 62.90±6.30, 38.73±3.04 ve 1.29±0.19 bulunmuştur. Biniş süresi (BS), ejakulasyon süresi (ES) ve ejakulasyon etkinliğine (EJET) ilişkin en küçük kareler ortalamaları sırasıyla; 0.65±0.11 dk, 5.16±0.71 dk ve 0.05±0.006 olarak belirlenmiştir. Çalısmada 3? yas grubu koçlar kuyruk kaldırma, ses çıkarma, ejakulasyonlu biniş sayısı, ejakulasyon süresi ve ejakulasyon etkinliği bakımından 2 yas grubu koçlardan üstün bulunmuştur (P<0.05). Eşeysel etkinlik testinin özellikle 2 yaslı koçlarda incelenen özellikler bakımından bir iyileşme sağlamadığı gözlenmiştir.