Consumers are growing increasingly dependent on Online Customer Reviews (OCRs) when making consumption decisions, more so for services due to their intangibility and variability. To this end, we advance a research model that explores how numerical ratings and opinionated reviews, as key constituents of OCRs, affects consumersâ€™ evaluation of service diagnosticity, which in turn enhances the latterâ€™s decision making process. Furthermore, we postulate that consumersâ€™ preference structure will determine the effectiveness of numerical ratings and opinionated reviews on service diagnosticity. Our research model was subsequently validated via a field study that was conducted on a custom developed online restaurant review site. Results suggest that numerical rating and opinionated review can amplify the effectiveness and efficiency of consumersâ€™ decision making process by bolstering the latterâ€™s ability to diagnose a given service. Nevertheless, the effects of numerical ratings and opinionated reviews are moderated by consumersâ€™ preferences for content relevance and self-reference.