A computer-implemented method for data analysis is provided. A deep neural network (100) is provided for processing images and at least a part of a training dataset used for training the deep neural network, the deep neural network comprising a plurality of hidden layers, the training dataset including possible observations that can be input to the deep neural network; obtaining first sets of intermediate output values that are output from at least one of the plurality of hidden layers, each of the first sets of intermediate output values obtained by inputting a different one of the possible input images included in said at least the part of the training dataset; constructing a latent variable model using the first sets of intermediate output values, the latent variable model providing a mapping of the first sets of intermediate output values to first sets of projected values in a sub-space that has a dimension lower than a dimension of the sets of the intermediate outputs; receiving an observation to be input to the deep neural network; obtaining a second set of intermediate output values that are output from said at least one of the plurality of hidden layers by inputting the received observation to the deep neural network; mapping, using the latent variable model, the second set of intermediate output values to a second set of projected values; and determining whether or not the received observation is an outlier with respect to the training dataset based on the latent variable model and the second set of projected values.