Σύγκριση μεθόδων

	Εξαγωγή λέξεων-κλειδιών	TF-IDF	Θεματική Ανάλυση	Μοντελοποίηση Θεμάτων
Πεδίο	Εξόρυξη Κειμένου	Εξόρυξη Κειμένου	Ποιοτική Έρευνα	Βαθιά Μάθηση
Οικογένεια	Process / pipeline	Process / pipeline	Process / pipeline	Machine learning
Έτος προέλευσης	—	1988	2006	1999–2003
Δημιουργός	—	Salton & Buckley	Virginia Braun and Victoria Clarke	Hofmann, T. (pLSA, 1999); Blei, D. M., Ng, A. Y., & Jordan, M. I. (LDA, 2003)
Τύπος	NLP text-mining task	Text vectorization / term-weighting scheme	Method	Unsupervised generative probabilistic model
Θεμελιώδης πηγή	Mihalcea, R. & Tarau, P. (2004). TextRank: Bringing Order into Texts. EMNLP, 404-411.	Salton, G. & Buckley, C. (1988). Term-weighting approaches in automatic text retrieval. Information Processing & Management, 24(5), 513-523.	Braun, V., & Clarke, V. (2006). Using thematic analysis in psychology. Qualitative Research in Psychology, 3(2), 77–101.	Blei, D. M., Ng, A. Y., & Jordan, M. I. (2003). Latent Dirichlet Allocation. Journal of Machine Learning Research, 3, 993–1022.
Εναλλακτικές ονομασίες	keyphrase extraction, key term extraction, Anahtar Kelime Çıkarma (Keyword Extraction)	term weighting, tf-idf weighting, TF-IDF Vektörizasyonu	TA, Reflexive Thematic Analysis	Latent Semantic Analysis, probabilistic topic modeling, topic discovery, thematic modeling
Συναφείς	4	3	3	5
Σύνοψη	Keyword extraction is a natural-language-processing task that automatically identifies the words or phrases that best represent the content of a document. It turns a body of free text into a compact, ranked list of key terms, drawing on statistical, graph-based methods such as TextRank (Mihalcea & Tarau, 2004), or embedding-based methods such as KeyBERT (Grootendorst, 2020).	TF-IDF, introduced by Salton and Buckley (1988), is a term-weighting scheme that scores each word in a document by how often it appears there and how rare it is across the whole collection. It turns raw text into weighted document vectors, giving high weight to terms that are frequent in one document but uncommon elsewhere.	Thematic Analysis (TA) is a qualitative research methodology for identifying, analyzing, and reporting patterns (themes) in qualitative data. Developed systematically by Virginia Braun and Victoria Clarke (2006), TA is flexible and accessible, applicable across diverse theoretical frameworks and data types, making it one of the most widely used qualitative methods in psychology, health research, and social sciences.	Topic Modeling is a family of unsupervised probabilistic techniques for discovering latent thematic structure in large text collections. By learning which words tend to co-occur, models such as Latent Dirichlet Allocation (LDA) automatically surface coherent topics — each represented as a distribution over vocabulary — without requiring labelled data.