Moreover LDA leaves flexibility to assign a different topic to every observed word and a different proportion of topics for every block of text.
the joint distribution of a block of text b m and the latent variables of the model z m , θ m , Φ, given the hyperparameters α, β is further specified by: the likelihood of a block b m is derived as the marginal distribution obtained by summing over the z m,n and integrating out the distributions θ m and Φ.