1. A computer system for generating and applying a formula for calculating an expected conversion rate, the computer system comprising: an electronic memory storage configured to store modules; a computer processor configured to execute the modules comprising at least: a data access module configured to access from a data repository stated metadata and derived metadata elements, wherein the stated metadata elements and the derived metadata elements are for a plurality of products that led to prior user conversions, wherein stated metadata comprises attributes of a product that are obtained from a product description provided by advertisers or suppliers of the plurality of products in the inventory database, and wherein derived metadata comprises physical attributes of a product that are identified based on characteristics of the product and that are not stated in a product description provided by advertisers or suppliers of the plurality of products in the inventory database, a conversions module configured to determine a statistical relevance of each stated metadata element and each derived metadata element in deriving expected conversion rates, wherein the statistical relevance of each stated metadata element and each derived metadata element comprises a likelihood or predictability of at least one of a click-through and a lead generation and wherein the determination of the statistical relevance is based on the use of a linear or logistic regression analysis, a formula generation module configured to generate on a periodic basis a formula based on the determination, wherein the formula takes into account a plurality of stated metadata elements and derived metadata elements that have been determined to be statistically relevant to expected conversion rates, and a formula application module configured to apply the formula to a plurality of products in an inventory database to assign a predicted conversion rate for each of the plurality of products in the inventory database, wherein the predicted conversion rate relates to generating higher revenue.