I. Introduction
The rapid and continuous growth of online text data has created an unprecedented opportunity to mine big text data to discover knowledge and support many applications especially for optimization of decision making. Among many applications of text data mining, prediction of interesting variables based on relevant text data is especially interesting because it allows decision makers to "see" patterns behind the data that they would otherwise not be able to see or easily see, thus leading to better decision making. Since humans are involved in every application domain, they would generate text data in every application domain, which we can leverage for various prediction tasks, making text-based prediction useful in virtually all the application domains. Text-based prediction can also facilitate a variety of downstreaming applications [1], [2], [3].