Robust and Adversarial Data Mining

In the domain of data mining and machine learning, researchers have made significant contributions in developing algorithms handling clustering and classification problems. We develop algorithms under assumptions that are not met by previous works. (i) In adversarial learning, which is the study of machine learning techniques deployed in non-benign environments. We design an algorithm to show how a classifier should be designed to be robust against sparse adversarial attacks. Our main insight is that sparse feature attacks are best defended by designing classifiers which use L1 regularizers. (ii) The different properties between L1 (Lasso) and L2 (Tikhonov or Ridge) regularization has been studied extensively. However, given a data set, principle to follow in terms of choosing the suitable regularizer is yet to be developed. We use mathematical properties of the two regularization methods followed by detailed experimentation to understand their impact based on four characteristics. (iii) The identification of anomalies is an inherent component of knowledge discovery. In lots of cases, the number of features of a data set can be traced to a much smaller set of features. We claim that algorithms applied in a latent space are more robust. This can lead to more accurate results, and potentially provide a natural medium to explain and describe outliers. (iv) We also apply data mining techniques on health care industry. In a lot cases, health insurance companies cover unnecessary costs carried out by healthcare providers. The potential adversarial behaviours of surgeon physicians are addressed. We describe a specific con- text of private healthcare in Australia and describe our social network based approach (applied to health insurance claims) to understand the nature of collaboration among doctors treating hospital inpatients and explore the impact of collaboration on cost and quality of care. (v) We further develop models that predict the behaviours of orthopaedic surgeons in regard to surgery type and use of prosthetic device. An important feature of these models is that they can not only predict the behaviours of surgeons but also provide explanation for the predictions