Browsing by Subject "Classification accuracy"

Now showing 1 - 9 of 9

Open Access
Classification by voting feature intervals
(Springer, 1997-04) Demiröz, Gülşen; Güvenir, H. Altay
A new classification algorithm called VFI (for Voting Feature Intervals) is proposed. A concept is represented by a set of feature intervals on each feature dimension separately. Each feature participates in the classification by distributing real-valued votes among classes. The class receiving the highest vote is declared to be the predicted class. VFI is compared with the Naive Bayesian Classifier, which also considers each feature separately. Experiments on real-world datasets show that VFI achieves comparably and even better than NBC in terms of classification accuracy. Moreover, VFI is faster than NBC on all datasets. © Springer-Verlag Berlin Heidelberg 1997.
Open Access
Classification of multichannel ECoG related to individual finger movements with redundant spatial projections
(IEEE, 2011) Onaran, ibrahim; İnce, N. Fırat; Çetin, A. Enis
We tackle the problem of classifying multichannel electrocorticogram (ECoG) related to individual finger movements for a brain machine interface (BMI). For this particular aim we applied a recently developed hierarchical spatial projection framework of neural activity for feature extraction from ECoG. The algorithm extends the binary common spatial patterns algorithm to multiclass problem by constructing a redundant set of spatial projections that are tuned for paired and group-wise discrimination of finger movements. The groupings were constructed by merging the data of adjacent fingers and contrasting them to the rest, such as the first two fingers (thumb and index) vs. the others (middle, ring and little). We applied this framework to the BCI competition IV ECoG data recorded from three subjects. We observed that the maximum classification accuracy was obtained from the gamma frequency band (65200Hz). For this particular frequency range the average classification accuracy over three subjects was 86.3%. These results indicate that the redundant spatial projection framework can be used successfully in decoding finger movements from ECoG for BMI. © 2011 IEEE.
Open Access
A comparability and classification analysis of computerized adaptive and conventional paper- based versions of an English language proficiency reading subtest
(2022-01) Kaya, Elif
The current study compares the computerized adaptive test (CAT) and paper-based test (PBT) versions of an English language proficiency reading subtest in terms of psychometric qualities. The study also investigates classification performance of CATs not designed for classification purposes with reference to its PBT version. Real data-based simulations were conducted under varying test conditions. The results demonstrate that ability levels estimated by CATs and PBT are similar. A relatively larger item reduction can be obtained with 0.50 and 0.40 standard error thresholds and CATs terminated with 20, 25, and 30 items performed well with acceptable SE values. Reliability of CAT ability estimates was comparable and highly correlated with PBT estimates. For classification analysis, classification accuracy (CA) and classification consistency (CC) was also estimated using the Rudner method. Classification analyses were conducted on single and multiple cut-off points. The results showed that the use of a single cut-off score produced better classification performance, particularly for high and low ability groups. On the other hand, the use of multiple cut-off scores simultaneously yielded significantly lower classification performance. Overall, the results highlight the potential for CATs not designed specifically for classification to serve classification purposes and indicate avenues for further research.
Open Access
Extraction of sparse spatial filters using Oscillating Search
(IEEE, 2012) Onaran, İbrahim; İnce, N. Fırat; Abosch, A.; Çetin, A. Enis
Common Spatial Pattern algorithm (CSP) is widely used in Brain Machine Interface (BMI) technology to extract features from dense electrode recordings by using their weighted linear combination. However, the CSP algorithm, is sensitive to variations in channel placement and can easily overfit to the data when the number of training trials is insufficient. Construction of sparse spatial projections where a small subset of channels is used in feature extraction, can increase the stability and generalization capability of the CSP method. The existing 0 norm based sub-optimal greedy channel reduction methods are either too complex such as Backward Elimination (BE) which provided best classification accuracies or have lower accuracy rates such as Recursive Weight Elimination (RWE) and Forward Selection (FS) with reduced complexity. In this paper, we apply the Oscillating Search (OS) method which fuses all these greedy search techniques to sparsify the CSP filters. We applied this new technique on EEG dataset IVa of BCI competition III. Our results indicate that the OS method provides the lowest classification error rates with low cardinality levels where the complexity of the OS is around 20 times lower than the BE. © 2012 IEEE.
Open Access
Hareket geçmişi görüntüsü yöntemi ile Türkçe işaret dilini tanima uygulaması
(IEEE, 2016-05) Yalçınkaya, Özge; Atvar, A.; Duygulu, P.
İşitme ve konuşma engelli bireylerin toplum içerisinde diger bireylerle sağlıklı şekilde iletişim kurabilmeleri açısından işaret dili çok önemli bir role sahiptir. Ne yazık ki işaret dilinin toplumda sadece duyarlı insanlar tarafından bilindiği ve bu sayının da azlıgı dikkat çekmektedir. Yaptığımız çalışma kapsamındaki amaç, geliştirdiğimiz sistem sayesinde işitme veya konuşma engeli mevcut olan bireylerin diğer bireylerle olan iletişiminde iyileşme sağlamaktır. Bu amaç doğrultusunda kameradan alınan işaret diline ait hareket bilgisi tanınabilmekte ve o hareketin ne anlama geldiği daha önceden eğitilen işaret diline ait hareket bilgileri ile karşılaştırılarak bulunabilmektedir. Hareket bilgilerinin kameradan alınan görüntülerden çıkarılması aşamasında "Hareket Geçmişi Görüntüsü" yöntemi kullanılmıştır. Bu bağlamdaki sınıflandırma işlemi için de "En Yakın Komşuluk" algoritması kullanılmıştır. Sonuç olarak geliştirilen sistem, eğitim kümesini kullanarak işaret dili hareketi için bir metin tahmin etmektedir. Toplamdaki sınıflandırma başarısı %95 olarak hesaplanmıştır.
Open Access
Machine-based learning system: classification of ADHD and non-ADHD participants
(IEEE, 2017) Öztoprak, H.; Toycan, M.; Alp, Y. K.; Arıkan, Orhan; Doğutepe, E.; Karakaş, S.
Attention-deficit/hyperactivity disorder (ADHD) is the most frequent diagnosis among children who are referred to psychiatry departments. Although ADHD was discovered at the beginning of the 20th century, its diagnosis is confronted with many problems. In this paper, a novel classification approach that discriminates ADHD and non-ADHD groups over the time-frequency domain features of ERP recordings is presented. Support Vector Machine-Recursive Feature Elimination (SVM-RFE) was used to obtain best discriminating features. When only three of these features were used the accuracy of classification reached to 98%, and use of six features further improved classification accuracy to 99.5%. The proposed scheme was tested with a new experimental setup and 100% accuracy is obtained. The results were obtained using RCV. The classification performance of this study suggests that TFHA can be employed as a core component of the diagnostic and prognostic procedures of various psychiatric illnesses.
Open Access
Multifont Ottoman character recognition
(IEEE, 2000) Öztürk, Ali; Güneş, S.; Özbay, Y.
Ottoman characters from three different fonts are used character recognition problem, broadly speaking, is transferring a page that contain symbols to the computer and matching these symbols with previously known or recognized symbols after extraction the features of these symbols via appropriate preprocessing methods. Because of silent features of the characters, implementing an Ottoman character recognition system is a difficult work. Different researchers have done lots of works for years to develop systems that would recognize Latin characters. Although almost one million people use Ottoman characters, great deal of whom has different native languages, the number of studies on this field is insufficient. In this study 28 different machine-printed to train the Artificial Neural Network and a %95 classification accuracy for the characters in these fonts and a %70 classification accuracy for a different font has been found.
Open Access
A signal representation approach for discrimination between full and empty hazelnuts
(IEEE, 2007) Onaran, İbrahim; İnce, N. F.; Tevfik, A. H.; Çetin, A. Enis
We apply a sparse signal representation approach to impact acoustic signals to discriminate between empty and full hazelnuts. The impact acoustic signals are recorded by dropping the hazelnut shells on a metal plate. The impact signal is then approximated within a given error limit by choosing codevectors from a special dictionary. This dictionary was generated from sub-dictionaries that are individually generated for the impact signals corresponding to empty and full hazelnut. The number of codevectors selected from each sub-dictionary and the approximation error within initial codevectors are used as classification features and fed to a Linear Discriminant Analysis (LDA). We also compare this algorithm with a baseline approach. This baseline approach uses features which describe the time and frequency characteristics of the given signal that were previously used for empty and full hazelnut separation. Classification accuracies of 98.3% and 96.8% were achieved by the proposed approach and base algorithm respectively. The results we obtained show that sparse signal representation strategy can be used as an alternative classification method for undeveloped hazelnut separation with higher accuracies.
Open Access
Subset selection with structured dictionaries in classification
(EURASIP, 2007) İnce, N. F.; Göksu, F.; Tewfik, A. H.; Onaran, İbrahim; Çetin, A. Enis
This paper describes a new approach for the selection of discriminant time-frequency features for classification. Unlike previous approaches that use the individual discrimination power of expansion coefficients, the proposed approach selects a subset of features by implementing a classifier directed pruning of an initial redundant set of candidate features. The candidate features are calculated from a structured redundant time-frequency analysis of the signal, such as an undecimated wavelet transform. We show that the proposed approach has a performance that is as good as or better than traditional classification approaches while using a much smaller number of features. In particular, we provide experimental results to demonstrate the superior performance of the algorithm in the area of impact acoustic classification for food kernel inspection. The proposed algorithm achieved 91.8% and 98.5% classification accuracies in separating open shell from closed shell pistachio nuts and discriminating between empty and full hazelnuts respectively. Traditional methods used in this area resulted in 82% and 97% classification accuracies respectively.