Tid: 20 oktober 2017 kl 10.15-11.15.

Föredragshållare: Kristoffer Brodin

Titel: Statistical Machine Learning from Classification Perspective: Prediction of Household Ties for Economical Decision Making

Abstract In modern society, many companies have large data records over their individual customers, containing information about attributes, such as name, gender, marital status, address, etc. These attributes can be used to link costumers together, depending on whether they share some sort of relationship with each other or not. In this thesis the goal is to investigate and compare methods to predict relationships between individuals in the terms of what we define as a household relationship, i.e. we wish to identify which individuals are sharing living expenses with one another. The objective is to explore the ability of three supervised statistical machine learning methods, namely, logistic regression (LR), artificial neural networks (ANN) and the support vector machine (SVM), to predict these household relationships and evaluate their predictive performance for different settings on their corresponding tuning parameters. Data over a limited population of individuals, containing information about household affiliation and attributes, were available for this task. In order to apply these methods, the problem had to be formulated on a form enabling supervised learning, i.e. a target and input predictors, based on the set of attributes associated with each individual, had to be derived. We have presented a technique which forms pairs of individuals un- der the hypothesis H₀, that they share a household relationship, and then a test of significance is constructed. This technique transforms the problem into a standard binary classification problem. A sample of observations could be generated by randomly pair individuals and using the available data over each individual to code the corresponding outcome on Y and X for each random pair. For evaluation and tuning of the three supervised learning methods, the sample was split into a training set, a validation set and a test set.

We have seen that the prediction error, in term of misclassification rate, is very small for all three methods since the two classes, H₀ is true, and H₀ is false, are far away from each other and well separable. The data have shown pronounced linear separability, generally resulting in minor differences in misclassification rate as the tuning parameters are modified. However, some variations in the prediction results due to tuning have been observed, and if also considering computational time and requirements on computational power, optimal settings on the tuning parameters could be determined for each method. Comparing LR, ANN and SVM, using optimal tuning settings, the results from testing have shown that there is no significant difference between the three methods performances and they all predict well. Nevertheless, due to difference in complexity between the methods, we have concluded that SVM is the least suitable method to use, whereas LR most suitable. However, the ANN handles complex and non-linear data better than LR, therefore, for future application of the model, where data might not have such a pronounced linear separability, we find it suitable to consider ANN as well.

This thesis has been written at Svenska Handelsbanken, one of the large major banks in Sweden, with offices all around the world. Their headquarters are situated in Kungsträdgården, Stockholm. Computations has been performed using SAS software and data have been processed in SQL relational database management system.

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