1. A method for updating a query tagging model using one or more stratified lexicons comprising: creating a list data structure comprising a set of lists, wherein a list comprises one or more phrases; creating seed distribution data comprising one or more phrases, wherein a phrase comprises a lexicon probability distribution; creating a sub-graph based upon the list data structure and the seed distribution data; executing a graph learning technique upon the sub-graph to create an expanded set of phrases, wherein a phrase comprises an updated lexicon probability distribution; creating one or more stratified lexicons based upon the expanded set of phrases; and updating a query tagging model using the one or more stratified lexicons as lexicon features.