So far, we have explain the different types of data that we collected, that have the potential, according the various hypotheses, to affect the impact and usefulness of the reviews. In this section, we present the results of our explanatory econometric analysis, which will examine the importance of each factor. Through our analysis, we aim to provide a better understanding of how customers are affected by the reviews. (In the next section, we will describe our predictive model, based on machine learning techniques.) In Section 4.1 we analyze the effect of different review and reviewer characteristics on product sales. Our results show what factors are important for a merchant to observe. Then, in Section 4.2 we presents our analysis on how different factors affect the helpfulness of a review.