Luis studies a newspaper's attitudes towards candidates for the position of Police Chief by counting the number of positive and negative comments attributed to each candidate. Luis's research approach is an example.

Luis is applying content analysis.

Explanation:

Under this approach, a person analyses concepts or themes in a text, which can later be quantified. After retrieving the data, it must be compared and evaluated.

A person might apply content analysis in written information, conversations and any other form of communication. The focus should be in the message.