Returns
		-------
		PriorFactory

def use_general_term_frequencies(self):
		'''
		Returns
		-------
		PriorFactory
		'''
		tdf = self._get_relevant_term_freq()
		bg_df = self.term_doc_mat.get_term_and_background_counts()[['background']]
		bg_df = pd.merge(tdf,
		                 bg_df,
		                 left_index=True,
		                 right_index=True,
		                 how='left').fillna(0.)
		self._store_priors_from_background_dataframe(bg_df)
		return self