Table 1. Classification techniques used in predicting helpful reviews.

Feature analysis in predicting helpful reviews.

Features	Author., year	Olmedilla, Martínez-Torres & Toral (2022)	Son, Kim & Koh (2021)	Woo & Mishra (2021)	Akbarabadi & Hosseini (2020)	Malik (2020)	Anh, Nagai & Nguyen (2019)	Eslami, Ghasemaghaei & Hassanein (2018)	Malik & Hussain (2018)	Liu et al. (2017)	Menner et al. (2016)	Qazi et al. (2016)	Yang, Chen & Bao (2016)	Huang et al. (2015)	Krishnamoorthy (2015)	Yang et al. (2015)	Zhang et al. (2015)	Martin & Pu (2014)	Zeng et al. (2014)	Zhang, Qi & Zhu (2014)	Momeni et al. (2013)	Korfiatis, García-Bariocanal & Sánchez-Alonso (2012)	Min & Park (2012)	Wu, Van der Heijden & Korfiatis (2011)	Ghose & Ipeirotis (2010)	O’Mahony & Smyth (2010)	Susan & David (2010)	Otterbacher (2009)	Liu et al. (2008)	Weimer & Gurevych (2007)
Linguistic features	Length of Sentence					X		X	X	X										X								X	X
	Emotional Words									X						X	X	X					X	X
	Term Frequency	X								X	X		X			X	X	X						X
	Length of Review				X	X		X				X	X			X	X		X					X	X	X	X			X
	Uppercase Words																X									X
	Verb’s Type																						X
	Complemented Words																						X
	Personal Information																								X
	Number of Sentences in a Review												X					X		X				X		X		X
	Describe Same Objects Repeatedly										X
	Describe about Name Entities																				X
	Opinion Words																												X
	Multiword Expression											X
	Number of Reviews of Review				X															X
	Information of Products												X
	Information of Services												X
	Information of Price												X
	Number of Adjective and Adverbs								X											X
	Complex Words																									X
	Large Number of Syllabus																									X			’
	Length of Character					X
Metadata Features	Rating	X	X	X	X	X			X		X	X	X	X				X	X			X	X	X	X		X	X	X	X
	Reviewer Identity			X	X								X	X											X
	Marked as Helpful		X	X	X	X	X	X				X		X	X				X	X		X			X		X	X
	Voted as Helpful		X	X	X	X	X					X		X	X				X	X		X			X		X	X
	Reviewing Date		X	X	X	X						X			X					X		X						X	X
	Title of Review	X		X	X	X			X													X
Semantic features	Exclamation Marks									X			X			X		X												X
	Less Spelling Mistake																X								X					X
	Compare or “Adjective + er than”																		X
	URL																													X
	Quote Function																													X
	Question Marks																													X
	Cue Words																						X
	Less Non-English Words																								X
	Higher Punctuation Marks																				X
	More Hyperlink																				X
	Sign @ for Replying																				X
Lexical features	Topic Related Words										X								X		X
	Pros and “Cons” String																		X
	Effective Tense																						X
	Describe Products’ Characteristics																								X
	Describe Other Products as Alternate																								X
	Topic Related Nouns, Verbs and Adjectives																	X						X
	Topic Related Nouns and Verbs								X		X
Readability features	Readability				X				X						X			X			X			X	X	X		X	X
Subjectivity feature	Subjectivity				X				X						X										X
Polarity feature	Polarity of Sentence				X	X	X	X	X	X			X				X	X		X				X					X