Table 4. The optimal number of topics is determined by different methods for different topic models.

The best results are highlighted in bold.

Datasets	Topic models	Methods
		Elbow method	AQDEB	Stability analysis	AICDR
BBCsport	LDA	13	13	5	5
	NMF	3	6	4	4
	K-Means	5	13	5	5
BBCNews	LDA	3	17	5	6
	NMF	3	19	2	5
	K-Means	3	16	6	6
Reuters	LDA	3	12	3	3
	NMF	3	7	4	3
	K-Means	3	13	3	3
AGNews	GSDMM	3	19	3	4
	SeaNMF	3	16	3	5
Snippets-1	GSDMM	4	12	4	4
	SeaNMF	18	4	4	4
Snippets-2	GSDMM	3	19	3	3
	SeaNMF	3	11	3	3