appending a client side routine to a Web page provided by a Web server, wherein the Web page includes content data;

sending the Web page to a plurality of client nodes; and

displaying the Web page to a plurality of users located at respective client nodes, and in response to the Web page being displayed to each user, each client node initiating the client side routine to perform the following:

detecting in-view user activities associated with each respective user browsing the Web page, wherein the in-view user activities are associated with in-view response data reflecting whether or not the content data was viewable or partially viewable to each respective user;

collecting data reflecting the in-view user activities, wherein the collected data includes information indicating the proportion of content actually viewable to a respective user, wherein the collected data is stored in a client side data stored;

detecting a client side trigger event, wherein each client side trigger event is associated with each respective client side data store being filled with the collected data above a predetermined threshold level; and

sending the collected data to the Web server in response to the detected client side trigger event; and

analyzing the collected data to determine user in-view characteristic data reflecting whether the content was viewable or partially viewable by the respective user.