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    Öğe
    Analysis of Plant Protection Studies with Excess Zeros Using Zero-Inflated and Negative Binomial Hurdle Models
    (Gazi Univ, 2010) Yesdlova, Abdullah; Kaya, Yilmaz; Kaki, Baris; Kasap, Ismail
    In this study, the analysis of data with many zeros for plant protection area was carried out by using the models of Poisson Regression (PR), negative binomial (NB) regression, zero-inflated Poisson (ZIP) regression, zeroinflated negative binomial (ZINB) regression, and negative binomial hurdle (NBH) model. As zero-inflated observations are too much in the studies, done in the plant protection area; models considering zero-inflated observations are frequently required. Mites (Acari: Tetranychidae; Stigmaeidae), the basic material of this study, can reach to quite high amounts under convenient temperature (18-32 degrees C temperature). The fact that deviance obtained from PR model together with Pearson Chi-square and deviance goodness of statistics came about quite higher than the value of (1) represented that there was an overdispersion in data set. In the selection of appropriate regression model, Akaiki information criteria and Bayesian information criteria were used. At the end of these information criteria, ZINB regression was chosen as the best model. In ZINB model, the effects of Zetzellia mali, temperature, and periods were significant on the total P. ulmi number (p<0.01), while applying insecticide was insignificant (p>0.05).
  • [ X ]
    Öğe
    Born early, perform better: The impact of relative age on performance in Turkish youth basketball
    (Sage Publications Ltd, 2025) Akinci, Yasin; Yapar, Ahmet; Kaki, Baris
    This study investigated the relative age effect (RAE) and its impact on performance in male basketball players participating in Turkish youth championships across U14, U16, and U18 age categories between 2017 and 2023 except 2020-2021 because of COVID-19 pandemics. An archival data model was employed, analysing data from 3113 players between 2017 and 2023. The months of birth were divided into four three-month periods and called Q1 to Q4. Statistical analyses included Chi-square tests with odds ratios, Welch ANOVA, and principal component analysis (PCA) used to visualize performance variable structures. Results indicated a significant RAE across all age groups, with Q1-born players consistently overrepresented and demonstrating superior performance in key metrics such as playing time, points, field goals, and efficiency score. The RAE was most pronounced in the U14 category, peaked at U16, and, while still present, was less prominent in U18, suggesting a convergence of biological maturity and the increasing influence of technical-tactical skills at older ages. PCA further revealed that early-born players were more likely to occupy central and productive roles on the court. These findings emphasize that coaches and policy-makers should consider RAE in their selection processes to ensure that long-term potential is not overlooked due to initial age-related disparities.