Multi-Dimensional Causal Discovery

We propose a method for learning causal relations within high-dimensional tensor data as they are typically recorded in non-experimental databases. The method allows the simultaneous inclusion of numerous dimensions within the data analysis such as samples, time and domain variables construed as tensors. In such tensor data we exploit and integrate non-Gaussian models and tensor analytic algorithms in a novel way. We prove that we can determine simple causal relations independently of how complex the dimensionality of the data is. We rely on a statistical decomposition that flattens higher-dimensional data tensors into matrices. This decomposition preserves the causal information and is therefore suitable for structure learning of causal graphical models, where a causal relation can be generalised beyond dimension, for example, over all time points. Related methods either focus on a set of samples for instantaneous effects or look at one sample for effects at certain time points. We evaluate the resulting algorithm and discuss its performance both with synthetic and real-world data.

Sit-to-Stand Movement Recognition Using Kinect

This paper examines the application of machine-learning techniques to human movement data in order to recognise and compare movements made by different people. Data from an experimental set-up using a sit-to-stand movement are first collected using the Microsoft Kinect input sensor, then normalized and subsequently compared using the assigned labels for correct and incorrect movements. We show that attributes can be extracted from the time series produced by the Kinect sensor using a dynamic time-warping technique. The extracted attributes are then fed to a random forest algorithm, to recognise anomalous behaviour in time series of joint measurements over the whole movement. For comparison, the k-Nearest Neighbours algorithm is also used on the same attributes with good results. Both methods’ results are compared using Multi-Dimensional Scaling for clustering visualisation