This paper covers mixing different types: http://www.csie.ntu.edu.tw/~b97053/paper/Rendle2010FM.pdf http://www.csie.ntu.edu.tw/~b97053/paper/Rendle2010FM.pdf (t

This paper covers mixing different types: http://www.csie.ntu.edu.tw/~b97053/paper/Rendle2010FM.pdf http://www.csie.ntu.edu.tw/~b97053/paper/Rendle2010FM.pdf (this paper covers a related but different technique). See figure 1 for an example of mixing ratings, indicator variables, and time into a single matrix.