Opinion Digger: An Unsupervised Opinion
Miner from Unstructured Product Reviews
Samaneh Moghaddam, Martin Ester
CopyRight@luzhonghao
Abstract
• Propose an unsupervised method for aspect
extraction from unstructured reviews using
known aspects.
• Introduce an unsupervised method for aspect
rating(on a scale from 1 to 5)based on the rating
guideline.
2
Lab for Internet Software Technologies
Problem Definition
Known
aspects
Output
aspects
3
Lab for Internet Software Technologies
Aspect Extraction
• Finding frequent noun phrases
• Mining opinion patterns
• Filtering out non-aspects
4
Lab for Internet Software Technologies
Finding Frequent Noun Phrases
• Hypothesis:those nouns that are frequent noun
phrases as a set of potential aspects
• Apply Apriori algorithm to find all multi-part
noun phrases which are frequent.
(support value=1%)
5
Lab for Internet Software Technologies
Mining Opinion Patterns
• Finds matching phrases for each of the known
aspects.It searches for each known aspect in the
reviews and finds its nearest adj. in that
sentence segment as corresponding sentiment.
• Saved the matching phrase and picks the POS
tags of all words as a pattern.
• After mining all POS patterns, use
GSP(Generalized Sequential Pattern) to find
frequent patterns(sup=1%)
6
Lab for Internet Software Technologies
Filtering out non-aspects
• Pnum: whitch is the number of opinion patterns
that are matched at least once by the potential
aspect.
• If pnum < 2: eliminate the aspect
7
Lab for Internet Software Technologies
Compute Aspect Rating
• For each aspect,extracts the nearest adj. as its
sentiment.
• For each sentiment of the every aspect of a
product,search in the WordNet synonymy
graph to find two rated synonyms from the
rating guideline .(can see them from the
website Epinion.com)
• Compute the rating of each sentment
8
Lab for Internet Software Technologies
Sentiment rating space
9
Lab for Internet Software Technologies
Compute each sentiment
10
Lab for Internet Software Technologies
Experimental results
11
Lab for Internet Software Technologies
Evaluation of Aspect Extraction
12
Lab for Internet Software Technologies
Thank you!
13
Lab for Internet Software Technologies