Empirically determine the appropriate number of topics. This plot demonstrates the number of relevant topics found in LDA models built with different number of topics. The appropriate number used for building the LDA model is determined when the number of relevant topics found stops to increase or starts to decrease. The data here shows that the 15-topic LDA model yielded 10 relevant topics for Alzheimer's disease gene set and 9 for Crohn's disease gene set. For osteoporosis, 3 relevant topics were found in the 5-topic LDA model.