Perform Sentiment Analysis

Sentiment analysis identifies positive or negative sentiments that are expressed within text.

For example, a business owner may want to analyse public sentiment toward their brand, or a police investigator may want to identify opinions expressed publicly by persons of interest in a criminal investigation.

Where possible, sentiment analysis can identify cases where sentiments are expressed towards a specific entity, and by a specific entity. This enables you to answer the question ‘Who expressed what sentiment about what?’ The sentiment analysis capability creates links between the sentiment phrase that was used and the entity toward which it was expressed. A link is also created between the entity that expressed the sentiment and the entity towards which it was expressed.

To perform a sentiment analysis on a collection you need to:

When the documents have been ingested or reprocessed, the positive and negative sentiments are marked up in the documents. You can view them by clicking on individual documents and by creating a network.

Create a dictionary of custom sentiment terms

If you want to identify specific sentiments in a collection you can create a dictionary for this purpose and add the terms to it. Depending on the type of sentiment analysis being conducted, you may focus on different words.

The sentiment analysis capability will apply concepts such as negation to all custom words, so aim to use the shortest, relevant word or term.

For example, if you want to capture the sentiment ‘not long-lasting’ in a sentence such as ‘The batteries were not very long-lasting’, add the word ‘long-lasting’ to the positive sentiment phrases section of the dictionary. The sentiment analysis capability will automatically process the negation ‘not’ and accurately tag the phrase ‘not very long-lasting’ as a negative sentiment. The capability will also check for other negations such as ‘isn’t’, ‘don’t’ and ‘wouldn’t’.

If you were to add the phrase ‘not long-lasting’ to the negative phrases section of the dictionary, the capability would only detect it when it appeared in that exact form. The phrase ‘not very long-lasting’ would therefore be missed.

By adding only the relevant word or term to the positive dictionary, the term will be tagged correctly when it is used in both positive sentiments (even where phrases begin with intensifiers like ‘very’ and ’extremely’), and negative sentiments.

To create a dictionary of custom sentiment terms, create a new dictionary with a name that reflects its purpose. For information about dictionaries see Dictionaries.

  1. Create a new dictionary with a name that reflects its purpose. For information about dictionaries see Dictionaries.

  2. Open the document processing configuration you will use for sentiment analysis and add the dictionary to the Dictionaries (Early Stage) section.

Perform a sentiment analysis

To perform a sentiment analysis:

  1. Open the project that contains the collection in which you want to analyse sentiment.
  2. Make sure that you have created a document processing configuration where sentiment analysis has been enabled, and that you have specified the ontology classes to which sentiments can be linked and/or attributed (see Ontology).
  3. Make sure that, in the Document Processing (in rule order) section of the ingestion configuration you are using, select the document processing configuration you have set up for sentiment analysis (from the previous step).
  4. If you have created a custom dictionary of sentiments, make sure you have added it to the Dictionaries (Early Stage) section of the document processing configuration.
  5. Do one of the following:
    • If you have not yet ingested the documents on which you want to perform a sentiment analysis, ingest them (for help see Add (Ingest) Documents).
    • If you have ingested the documents, click Collections on the Main Navigation Bar then select the collection on which you want to perform the sentiment analysis. Click Reprocess.
  6. To view the results of the sentiment analysis, do one of the following:
    • Select a document in the collection. Positive and negative sentiments are marked.
    • Create a network based on the collection, selecting positive and/or negative sentiment nodes and links.