3.3 Sentiment Model The design of the sentiment model used in our system was based on the assumption that the opinions expressed would be highly subjective and contextualized . Therefore , for generating data for model training and testing , we used a crowd-sourcing approach to do sentiment annotation on in-domain political data . To create a baseline sentiment model , we used Amazon Mechanical Turk ( AMT ) to get as varied a population of annotators as possible . We designed an interface that allowed annotators to perform the annotations outside of AMT so that they could participate anonymously .