Browsing by Subject "Decision Support System"

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Open Access
Estimating the chance of success and suggestion for treatment in IVF
(2013) Mısırlı, Gizem
In medicine, the chance of success for a treatment is important for decision making for the doctor and the patient. This thesis focuses on the domain of In Vitro Fertilization (IVF), where there are two issues: the first one is the decision on whether or not go with the treatment procedure, the second one is the selection of the proper treatment protocol for the patient. It is important for both the doctor and the couple to have some idea about the chance of success of the treatment after the initial evaluation. If the chance of success is low, the patient couple may decide not to proceed with this stressful and expensive treatment. Once a decision for treatment is made, the next issue for the doctors is the choice of the treatment protocol which is the most suitable for the couple. Our first aim is to develop techniques to estimate the chance of success and determine the factors that affect the success in IVF treatment. So, we employ ranking algorithms to estimate the chance of success. The ranking methods used are RIMARC (Ranking Instances by Maximizing the Area under the ROC Curve), SVMlight (Support Vector Machine Ranking Algorithm) and RIkNN (Ranking Instances using k Nearest Neighbour). All of these three algorithms learn a model to rank the instances based on their score values. RIMARC is a method for ranking instances by maximizing the area under the ROC curve. SVMlight is an implementation of Support Vector Machine for ranking instances. RIkNN is a k Nearest Neighbour (kNN) based algorithm that is developed for ranking instances based on similarity metric. We also used RIwkNN, which is the version of RIkNN where the features are assigned weights by experts in the domain. These algorithms are compared on the basis of the AUC of 10-fold stratified cross-validation. Moreover, these ranking algorithms are modified as a classification algorithm and compared on the basis of the accuracy of 10-fold stratified cross-validation. As a by-product, the RIMARC algorithm learns the factors that affect the success in IVF treatment. It calculates feature weights and creates rules that are in a human readable form and easy to interpret. After a decision for a treatment is made, the second aim is to determine which treatment protocol is the most suitable for the couple. In IVF treatment, many different types of drugs and dosages are used, however, which drug and the dosage are the most suitable for the given patient is not certain. Doctors generally make their decision based on their past experiences and the results of research published all over the world. To the best of our knowledge, there are no methods for learning a model that can be used to suggest the best feature values to increase the chance that the class label to be the desired one. We will refer to such a system as Suggestion System. To help doctors in making decision on the selection of the suitable treatment protocols, we present three suggestion systems that are based on well-known machine learning techniques. We will call the suggestion systems developed as a part of this work as NSNS (Nearest Successful Neighbour Based Suggestion), kNNS (k Nearest Neighbour Based Suggestion) and DTS (Decision Tree Based Suggestion). We also implemented the weighted version of NSNS using feature weights that are produced by the RIMARC algorithm. Moreover, we propose performance metrics for the evaluation of the suggestion algorithms. We introduce four evaluation metrics namely; pessimistic metric (mp), optimistic metric (mo), validated optimistic metric (mvo) and validated pessimistic metric (mvp) to test the correctness of the algorithms. In order to help doctors to utilize developed algorithms, we develop a decision support system, called RAST (Risk Analysis and Suggestion for Treatment). This system is actively being used in the IVF center at Etlik Z¨ubeyde Hanım Woman’s Health and Teaching Hospital.
Open Access
A rule-based reasoning decision support system for AS-532 cougar helicopters' maintenance personnel
(2004) Doğan, Hüseyin Kurtuluş
Improvements in the aviation technologies have made the aircrafts more reliable, more capable in terms of operational necessities and as a result more technological. Today, Turkish Army Aviation units possess helicopters that are equipped with the technologically up-to-date equipments. Those new generation helicopters brought their advantages in terms of performance, speed, and reliability as well as the disadvantages in terms of maintenance load, expensive parts and required deep system knowledge. At this point, there is a trade off that takes place between the development and the system integration and maintenance necessities of these ultimate equipments. Helicopter systems turn out to be more interactive. Those developments make it easier to fly for the user pilots, but more difficult to perform the maintenance necessities for the maintenance personnel. New maintenance necessities of the developed equipments and interactive systems make it more difficult to keep the helicopter fleets flying and operational. Furthermore this situation increases the need for the domain experts. Number of unexpected failures and the required time for fault isolation are increasing by the acquisitions of developed helicopters. Acquired experience is an important reference for the maintenance personnel in solving the problems as well as the technical documents of the helicopters. In this study, a decision support system in rule-based reasoning is formed in order to help AS-532 COUGAR helicopters’ maintenance personnel. Extraordinary failures, their possible causes, warning to users and recommended solution procedures are presented in the design of “case”. Users can reach to these cases by following the failure related attribute-value pairs. With the help of this decision support system, it will be possible to share the expertise of the COUGAR experts with the inexperienced personnel. As a result, the percentage of true “fault identification” will increase and required time for fault isolation will decrease. This expertise can also be used in training procedures.
Open Access
VISTA: a visual interactive method for solving MCDM problems
(1994) Tabanoğlu, Aslıhan
In this thesis, recognizing the need of interaction with DM (Decision Maker) in solving MCDM (Multiple Criteria Decision Making) problems, a practical interactive algorithm called VISTA (Visual Interactive Sequential Tradeoffs Algorithm) is developed, and a DSS (Decision Support System) is designed to assist DM to use judgement effectively. The algorithm operates by successively optimizing a chosen objective function while the remaining objectives are converted to constraining objectives by setting their satisficing values, one of which is parametrically varied. By plotting the maximum value of the main objective function versus the parameter varied, a tradeoff curve is constructed between the optimized and the parametrized objective, while assuring constraining objectives (satisficing values guaranteed). This tradeoff curve is presented to the DM, and the DM is asked to choose a compromise solution between these two objectives. This chosen point is used as the new satisficing value of the parametrized objective, and a new tradeoff curve is generated by parametrizing another constraining objective function’s right hand side and .so on. This interactive procedure is continued until the DM is satisfied with the current decision or some other termination criterion is met. Special features to facilitate the DM’s judgement (MRS (Marginal Rate of Substitution) Curve, Multiple Comparison Plots, Convergence Plots), and the start and the termination (Start, Terminate, a Hybrid Approach) of the algorithm are provided. Two example problems are worked out with VISTA to demonstrate the practicality of the algorithm. The model and the entire procedure are validated.