R: Mining Spatial, Text, Web, and Social Media Data

Case study 2 – Naive Bayes classifier

In the previous chapter, we described how Naive Bayes is a type of classifier, that is, a statistical model designed to estimate group membership of observations. If we have a sufficient amount of training data, we can use it to train or learn a statistical model that we can subsequently use to estimate the sentiment of other, unlabeled observations. The key assumption underlying this technique is that at least some words are used with different frequencies by those with positive and negative sentiments towards a particular target. This section walks through the implementation of Naive Bayes for sentiment classification.

For demonstrative purposes, we have scraped about 4,000 tweets using the methods set out ...