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Öğe ADAPTATION OF COGNITIVE STYLE INDICATOR: VALIDITY AND RELIABILITY STUDIES OF THE INDICATOR(Editura Univ Oradea, 2014) Aslan, Sevda; Gelbal, SelahattinCognitive Style Indicator (COSI) is a scale developed by Cools and Van den Broeck (2007) which evaluates cognitive style in university students. COSI is a five-point Likert-type scale consisting of 3 cognitive styles and 18 items. COSI cognitive styles are as follows: Knowing, planning, and creating. The aim of this study was to determine the validity and reliability of the university students. The study was conducted on 1851 university students. 1035 female and 816 male students participated in the study. The sampling group consisted of 1851 1st-4th year students studying at 63 universities during the fall 2012-2013 academic year. However, the data gathered from 331 respondents were excluded from the analysis due to incorrect or missing marking; therefore, the analysis was conducted using a 1520-person data set. The number of female students participating in the study was 885 and the number of male students participating in the study was 635. In addition, test-retest reliability method and internal consistency Analysis were used in order to evaluate the reliability of the scale. As a result of the factor analysis study, the COSI consisted of 18 items and 3 factors (knowing, planning, and creating). Exploratory and confirmatory factor analyses were carried out in order to test the construct validity of the scale. It was found that the Cronbach Alpha of the knowing, planning and creating were respectively 0.72, 0.77 and 0.80, and test-retest coefficients of the knowing, planning and creating were respectively 0.83, 0.87 and 0.93. Study findings revealed that this measurement tool can be used for Turkish university students as both a reliable and valid one.Öğe Development of Attitude to University Life Scale: Validity and Realibility Studies of Scale(Elsevier Science Bv, 2015) Aslan, Sevda; Gelbal, SelahattinThis study aims to develop a measurement tool that evaluates the attitude of university students to university life and also to conduct the validity of this measurement tool. Study group comprised of 355 students, 162 (45.63%) of whom were females with a mean age of 20.72 and 193 were males (54.37%) with a mean age of 20.93. Exploratory Factor Analyses were used in order to test the validity of the scale developed for this study. In addition, internal consistency analysis were used in order to evaluate the reliability of the scale. As a result of the factor analysis study, the Attitude to University Life Scale consisted of 25 items and 4 factors. Study findings revealed that this measurement tool can be used for Turkish university students as a valid one. (C) 2015 The Authors. Published by Elsevier Ltd.Öğe Development of Attitude to University Students Family Communication Scale: Validity and Realibility Studies of Scale(Elsevier Science Bv, 2015) Aslan, Sevda; Gelbal, SelahattinThis study aims to develop a measurement tool that evaluates the attitude of university students family communication and also to conduct the validity and reliability of this measurement tool. Study group comprised of 355 students, 144 (40.56%) of whom were females with a mean age of 20.58 and 211 were males (59.44%) with a mean age of 20.26. Exploratory Factor Analyses were used in order to test the validity of the scale developed for this study. In addition, internal consistency analysis were used in order to evaluate the reliability of the scale. As a result of the factor analysis study, the Attitude to University Students Family Communication Scale consisted of 28 items and 3 factors. Study findings revealed that this measurement tool can be used for Turkish university students as valid one. (C) 2015 The Authors. Published by Elsevier Ltd.Öğe Examining the Parameter Estimations of Simple and Complex Structured Tests with Various Dimensionality Properties Based on Multidimensional Item Response Theory(Assoc Measurement & Evaluation Education & Psychology, 2015) Eser, Derya Çakıcı; Gelbal, SelahattinUnder the scope of this study; parameter estimations of simple and complex structured two and three dimensional tests have been performed according to different test length and sample size conditions; according to the estimations, RMSE, bias and relation between estimated and actual parameters have been investigated. Research data has been generated by means of simulations according to requirements of two dimensional simple structure, two dimensional complex structure, three dimensional complex structure and three dimensional complex structure. The simulation conditions were test length (12 and 48 items) and sample size (1000, 2000 and 4,000). By intercrossing the simulation conditions (4 test structures x 2 test lengths x 3 sample sizes); 24 crossed conditions have been acquired. By fixing item and ability parameters and applying 25 replications; 600 data sets have been generated and analyzed. According to the results, parameter recovery of item parameters increases with the number of items and examinees. For each condition; d parameters have been estimated more accurately than a parameters on the same pattern. Parameter recovery of ability parameters is developed with the increase in test length. High correlation values acquired in the conditions where RMSE values are low. Additionally; suggestions on the required test length and sample size for accurate estimations are provided at the final stage of the study.Öğe Farklı Boyutluluk Özelliklerindeki Basit ve Karmaşık Yapılı Testlerin Çok Boyutlu Madde Tepki Kuramına Dayalı Parametre Kestirimlerinin İncelenmesi(2015) Eser, Derya Çakıcı; Gelbal, SelahattinBu çalışmada basit ve karmaşık yapıdaki iki ve üç boyutlu testlerin farklı test uzunluğu ve örneklem büyüklüğü koşullarında parametre kestirimleri yapılmış, kestirimlere ilişkin olarak elde edilen RMSE, yanlılık ve kestirilen parametreler ile gerçek parametreler arasındaki ilişki incelenmiştir. Çalışmanın verileri iki boyutlu basit, iki boyutlu karmaşık, üç boyutlu karmaşık ve üç boyutlu basit yapıya uygun olacak şekilde simülasyon yoluyla üretilmiştir. Veri setlerinin test uzunluğu 12 ve 48 madde; örneklem büyüklüğü 1000, 2000 ve 4000 olacak şekilde değiştirilmiştir. Bu şekilde ele alınan dört test yapısı ile 2 test uzunluğu ve 3 örneklem büyüklüğü koşulu çaprazlanarak (4x2x3) 24 koşul içeren desen oluşturulmuştur. Oluşturulan her koşula ilişkin olarak, madde ve birey parametreleri sabit tutulmak üzere, 25 tekrar yapılarak toplamda 600 veri seti oluşturulmuş ve analiz edilmiştir. Elde edilen sonuçlara göre madde parametrelerinin parametre kestirim iyiliği hem madde hem birey sayısındaki artışla artmaktadır. Ele alınan her bir koşulda d parametreleri aynı koşuldaki a parametrelerinden daha kararlı kestirilmiştir. Birey parametrelerinin kestirim iyiliği test uzunluğundaki artış ile artmaktadır. Yüksek korelasyon değerleri RMSE'nin düşük olduğu koşullarda elde edilmiştir. Ayrıca çalışmanın sonunda daha kararlı kestirim yapabilmek için gerekli test uzunluğu ve örneklem büyüklüğüne ilişkin öneriler geliştirilmeye çalışılmıştır.Öğe Genellenebilirlik kuramı ve lojistik regresyona dayalı hesaplanan puanlayıcılar arası tutarlığın karşılaştırılması(2013) Eser, Derya Çakıcı; Gelbal, SelahattinAraştırmanın amacı G Kuramı ve LR analizinden yararlanarak gerçekleştirilen bir performans puanlamada ortaya çıkan puanlayıcı tutarlığını belirlemek ve karşılaştırmaktır. Araştırmada 106 öğrenciye 15 maddelik bir ölçme aracı verilmiş, öğrencilerin verdikleri cevaplar üç puanlayıcı tarafından dereceli puanlama anahtarı kullanılarak puanlanmıştır. Puanlama ile elde edilen veri seti, G kuramı ve lojistik regresyon analizi ile madde bazında ve testin tamamına dayalı olarak analiz edilmiştir. Analiz sonucunda G kuramı ile elde edilen puanlayıcıvaryans bileşenleri ve toplam varyansı açıklama yüzdeleri ile LR analizi ile elde edilen sınıflama yüzdeleri yorumlanmıştır. Elde edilen bulgulara dayalı olarak G Kuramı ve LR analizinin puanlayıcılar arası tutarlığı belirlemede paralel sonuçlar ürettiği, ancak lojistik regresyon analizinin G kuramı kadar hassas çıktılar vermediği ve G kuramına göre daha yüzeysel bir istatistik olduğu sonucuna varılmıştır.Öğe The Interaction Effect of the Correlation between Dimensions and Item Discrimination on Parameter Estimation(Assoc Measurement & Evaluation Education & Psychology, 2018) Sahin, Sakine Gocer; Eser, Derya Cakici; Gelbal, SelahattinThere are some studies in the literature that have considered the impact of modeling multidimensional mixed structured tests as unidimensional. These studies have demonstrated that the error associated with the discrimination parameters increases as the correlation between dimensions increases. In this study, the interaction between items' angles on coordinate system and the correlations between dimensions was investigated when estimating multidimensional tests as unidimensional. Data were simulated based on two dimensional, and two-parameter compensatory MIRT model. Angles of items were determined as 0.15 degrees; 0.30 degrees; 0.45 degrees; 0.60 degrees and 0.75 degrees respectively. The correlations between ability parameters were set to 0.15, 0.30, 0.45, 0.60 and 0.75 respectively, which are same with the angles of discrimination parameters. The ability distributions were generated from standard normal, positively and negatively skewed distributions. A total of 75 (5 x 5 x 3) conditions were studied: five different conditions for the correlation between dimensions; five different angles of items and three different ability distributions. For all conditions, the number of items was fixed at 25 and the sample size was fixed at n = 2,000. Item and ability parameter estimation were conducted using BILOG. For each condition, 100 replications were performed. The RMSE statistic was used to evaluate parameter estimation errors, when multidimensional response data were scaled using a unidimensional IRT model. Based on the findings, it can be concluded that the pattern of RMSE values especially for discrimination parameters are different from the existing studies in the literature in which multidimensional tests were estimated as unidimensional.
