Table 2. Cross classification of the considered papers: according to the tackled thyroid disease and according to the various AI techniques, grouped also per macro-category.

	Thyroid diseases
AI group	AI technique	Hypothyroidism	Hyperthyroidism	Euthyroid disease	Thyroid cancer	Generic/others
	Naive BayesNB	Rao & Renuka (2020), Pasha & Mohamed (2020), Houari et al. (2016), Chandel et al. (2016), Duggal & Shukla (2020), Peya, Chumki & Zaman (2021), Riajuliislam, Rahim & Mahmud (2021), Juneja (2022)	Rao & Renuka (2020), Pasha & Mohamed (2020), Houari et al. (2016), Chandel et al. (2016), Duggal & Shukla (2020), Peya, Chumki & Zaman (2021), Juneja (2022)	Duggal & Shukla (2020), Islam et al. (2022)	Qin et al. (2021)	Juneja (2022), Kishor & Chakraborty (2021)
	Log regression LR	Pasha & Mohamed (2020) Riajuliislam, Rahim & Mahmud (2021)	Pasha & Mohamed (2020)		Qin et al. (2021)	Raisinghani et al. (2019), Chaubey et al. (2021)
Probabilistic approaches	Time Series Regression TSR	Chandio et al. (2016)	Chandio et al. (2016)	Chandio et al. (2016)
	Support Vector Machine SVM	Duggal & Shukla (2020), Shahid et al. (2019), Ahmed & Soomrani (2016), Tyagi, Mehra & Saxena (2018), Shen et al. (2016),Li et al. (2019b), Chandel et al. (2016), Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020), Pavya & Srinivasan (2017), Riajuliislam, Rahim & Mahmud (2021)	Duggal & Shukla (2020), Shahid et al. (2019), Ahmed & Soomrani (2016), Tyagi, Mehra & Saxena (2018), Shen et al. (2016), Li et al. (2019b), Chandel et al. (2016), Pavya & Srinivasan (2017)	Ahmed & Soomrani (2016), Shen et al. (2016), Li et al. (2019b), Duggal & Shukla (2020), Islam et al. (2022)	Raghavendra et al. (2018), Prochazka et al. (2019), Raghavendra et al. (2017), Qin et al. (2021), Shen et al. (2021)	Tyagi, Mehra & Saxena (2018), Kaur, Kumar & Kumar (2019),Kishor & Chakraborty (2021)
Kernel-based approaches	multi-kernel SVM	Kumar (2020)	Kumar (2020)	Kumar (2020)
	Decision Tree DT	Rao & Renuka (2020), Sidiq & Mutahar Aaqib (2019), Tyagi, Mehra & Saxena (2018), Hayashi (2017), Peya, Chumki & Zaman (2021), Riajuliislam, Rahim & Mahmud (2021), Juneja (2022)	Rao & Renuka (2020), Sidiq & Mutahar Aaqib (2019), Tyagi, Mehra & Saxena (2018), Hayashi (2017), Peya, Chumki & Zaman (2021), Juneja (2022)	Islam et al. (2022)	Hao et al. (2018)	Tyagi, Mehra & Saxena (2018), Raisinghani et al. (2019), Kaur, Kumar & Kumar (2019), Chaubey et al. (2021), Juneja (2022), Kishor & Chakraborty (2021)
	Decision stump DS		Jha et al. (2018)
	Random Forest RF	Sidiq & Mutahar Aaqib (2019), Shahid et al. (2019), Duggal & Shukla (2020), Riajuliislam, Rahim & Mahmud (2021), Juneja (2022)	Sidiq & Mutahar Aaqib (2019), Shahid et al. (2019), Imbus et al. (2017), Duggal & Shukla (2020), Juneja (2022)	Duggal & Shukla (2020) Islam et al. (2022)	Prochazka et al. (2019) Qin et al. (2021)	Pan et al. (2016), Prochazka et al. (2019), Raisinghani et al. (2019), Kaur, Kumar & Kumar (2019), Juneja (2022)
	Iterative Dichotomiser 3ID3	Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020)
Decision Tree approaches	Chi-squared Automatic Interaction DetectionCHAID	Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020)
	Recursive-Rule extraction Re-RX	Hayashi (2017)	Hayashi (2017)
	Case-based reasoning	Bentaiba-Lagrid et al. (2020)	Bentaiba-Lagrid et al. (2020)
	Rutherford Backscattering Spectrometry RBS		Imbus et al. (2017)
Rule-based approaches	Fuzzy RBS	Asaad Sajadi et al. (2019), Kumari & Sharma (2019)	Kumari & Sharma (2019)
	Artificial neural network ANN	Sidiq & Mutahar Aaqib (2019), Mahurkar & Gaikwad (2017), Tyagi, Mehra & Saxena (2018), Houari et al. (2016), Vivar et al. (2020),Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020)	Sidiq & Mutahar Aaqib (2019), Mahurkar & Gaikwad (2017), Tyagi, Mehra & Saxena (2018), Houari et al. (2016), Vivar et al. (2020)	Islam et al. (2022)	Ahmed et al. (2022), Cordes et al. (2021), Jin et al. (2021)	Tyagi, Mehra & Saxena (2018), Raisinghani et al. (2019), Kaur, Kumar & Kumar (2019), Santos et al. (2019), Kishor & Chakraborty (2021)
	Bidirectional Long Short-Term Memory - Long Short Term Memory (LSTM) BLSTM-LSTM	Yue et al. (2020)	Yue et al. (2020), Lu et al. (2020)			Chai (2020)
	Convolutional Neural Network CNN	Yue et al. (2020) Ananthi et al. (2022) Khan (2021)	Yue et al. (2020) Ananthi et al. (2022)		Yin et al. (2019), Yi et al. (2017), Lyu & Haque (2018), Li et al. (2019a), Moran et al. (2018), Ananthi et al. (2022), Chu, Zheng & Zhou (2021),Liu et al. (2021), Santillan et al. (2021), Song et al. (2022)	Poudel et al. (2019), Guo & Du (2019),Ananthi et al. (2022),Pi et al. (2022), Yang et al. (2021)
	Generative Adversarial Network GAN	Zhang, Huang & Lv (2020)	Zhang, Huang & Lv (2020)		Shi et al. (2020), Zhao et al. (2022)
	Capsule Network CN				Ai et al. (2022)
	RBF NN	Juneja (2022)	Juneja (2022)			Juneja (2022)
	Autoencoder	Saktheeswari & Balasubramanian (2021)	Saktheeswari & Balasubramanian (2021)		Saktheeswari & Balasubramanian (2021)
	Recurrent Neural Network RNN				Santillan et al. (2021)
Neural Network	Multilayer Perceptron MLP Back Propagation	Yue et al. (2020), Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020), Pavya & Srinivasan (2017), Hosseinzadeh et al. (2021), Juneja (2022)	Yue et al. (2020), Pavya & Srinivasan (2017), Hosseinzadeh et al. (2021), Juneja (2022)	Qin et al. (2021)	Juneja (2022)
Cluster-based approaches	K-Nearest Neighbors Algorithm KNN	Shahid et al. (2019), Tyagi, Mehra & Saxena (2018), Pasha & Mohamed (2020), Houari et al. (2016), Chandel et al. (2016), Pasha & Mohamed (2020), Peya, Chumki & Zaman (2021)	Shahid et al. (2019), Tyagi, Mehra & Saxena (2018), Pasha & Mohamed (2020), Houari et al. (2016), Chandel et al. (2016), Peya, Chumki & Zaman (2021)	Islam et al. (2022)	Qin et al. (2021)	Tyagi, Mehra & Saxena (2018), Kaur, Kumar & Kumar (2019),Chaubey et al. (2021),Kishor & Chakraborty (2021)
	AdaBoost	Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020), Yadav & Pal (2022), Priyadharsini & Sasikala (2022)	Priyadharsini & Sasikala (2022)	Islam et al. (2022)		Kishor & Chakraborty (2021)
	Stacking	Yadav & Pal (2022) Sidiq & Mutahar Aaqib (2019)	Sidiq & Mutahar Aaqib (2019), Jha et al. (2018)
	Bagging	Zarin Mousavi, Mohammadi Zanjireh & Oghbaie (2020), Yadav & Pal (2022),Priyadharsini & Sasikala (2022)	Priyadharsini & Sasikala (2022)		Qin et al. (2021)
	Vote ensemble	Sidiq & Mutahar Aaqib (2019), Yadav & Pal (2022)	Sidiq & Mutahar Aaqib (2019), Jha et al. (2018)	Islam et al. (2022)	Yin et al. (2019)	Pan et al. (2016)
Ensembles	Dynamic ensemble	Alam, Siddique & Adeli (2020)	Alam, Siddique & Adeli (2020)	Alam, Siddique & Adeli (2020)
	Semi supervised Learning
	Weighted Extreme Learning Machine WELM					Priya & Manavalan (2018)
	Extreme Learning Machine ELM	Pavya & Srinivasan (2017), Ma et al. (2018),Juneja (2022)	Pavya & Srinivasan (2017), Ma et al. (2018),Juneja (2022)			Juneja (2022)
Other Learning approaches	Amended fused TOPSIS-VIKOR for classification ATOVIC	Baccour (2018)	Baccour (2018)