Human activities are classified based on activity-related data and an activity-classification model trained using a classification-equalized training data set. A classification signal is generated based on the classifications. The classification-equalized training data set, may, for example, includes a first class having a first sequence length and a number of samples N, and one or more additional classes each having a respective sequence length tj and a respective number of samples Nj determined based on the number of samples N of the first class. For example, a respective sequence length tj and a respective number of samples Nj which satisfy: (i) Nj>N, for sequence length tj and (ii) Nj
