Personal safety device and method

A method of training a model for relating one or more potential personal safety incidents comprising an attack on an individual to features derivable from a data set comprising motion data and vital sign data, the method comprising:

• receiving a plurality of training data sets, each training set comprising motion data from one or more motion sensors associated with an individual over a training time period and vital sign data from one or more vital sign sensors associated with the individual over the training time period, the vital sign data comprising heart rate data;
• receiving for each training data set a label indicative of whether conditions corresponding to a personal safety incident comprising an attack on the individual occurred during the training time period;
• determining for each training data set a plurality of training features based on the motion data and the vital sign data, the plurality of training features comprising one or more motion features and one or more vital sign features, wherein determining the one or more vital sign features comprises determining, based on the heart rate data, a measure of heart rate variability;
• determining a measure of dependence between the labels and the one or more motion features and the one or more vital sign features comprising the measure of heart rate variability;
• and
• creating a model based on the determined measure of dependence, wherein the model is configured to relate a potential personal safety incident comprising an attack on an individual to features derivable from a data set comprising motion data and vital sign data.