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Sentiment Analysis based on Appraisal Theory and Functional Local ...

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5<br />

last paragraph, there is a positive evaluati<strong>on</strong> about a proposed federal immigrati<strong>on</strong><br />

law (“sensible policy”), as well a negative evaluati<strong>on</strong> of the current “failed immigrati<strong>on</strong><br />

system”, <strong>and</strong> a negative evaluati<strong>on</strong> of of Alabama’s law ascribed to “church<br />

leaders.”<br />

With this informati<strong>on</strong>, it’s possible to solve many more complicated sentiment<br />

tasks. C<strong>on</strong>sider a particular applicati<strong>on</strong> where the goal is to determine which political<br />

party the author of the editorial aligns himself with.<br />

Actors across the political<br />

spectrum have varying opini<strong>on</strong>s <strong>on</strong> both laws in this editorial, so it is not enough to<br />

determine that there is positive or negative sentiment in the editorial. Even when<br />

combined with topical text classificati<strong>on</strong> to determine the subject of the editorial<br />

(immigrati<strong>on</strong> law), a bag-of-words technique cannot reveal that the negative opini<strong>on</strong><br />

is about a state immigrati<strong>on</strong> law <strong>and</strong> the positive opini<strong>on</strong> is about the proposed federal<br />

immigrati<strong>on</strong> law. If the opini<strong>on</strong>s had been reversed, there would still be positive <strong>and</strong><br />

negative sentiment in the document, <strong>and</strong> there would still be topical informati<strong>on</strong><br />

about immigrati<strong>on</strong> law.<br />

Even breaking down the document at the paragraph or<br />

sentence level <strong>and</strong> performing text classificati<strong>on</strong> to determine the topic <strong>and</strong> sentiment<br />

of these smaller units of text does not isolate the opini<strong>on</strong>s <strong>and</strong> topics in a way that<br />

clearly correlates opini<strong>on</strong>s with topics. Using structured sentiment informati<strong>on</strong> to<br />

discover that the negative sentiment is about the Alabama law, <strong>and</strong> that the positive<br />

sentiment is about the federal law does tell us (presuming that we’re versed in United<br />

States politics) that the author of this editorial is likely aligned with the Democratic<br />

Party.<br />

It is also possible to use these structured opini<strong>on</strong>s to separate out opini<strong>on</strong>s<br />

about the federal immigrati<strong>on</strong> reform, <strong>and</strong> opini<strong>on</strong>s about the Alabama state law<br />

<strong>and</strong> compare them. Structured sentiment extracti<strong>on</strong> techniques give us the ability to<br />

make these kinds of determinati<strong>on</strong>s from text.

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