ADAPTIVE CONTACT WINDOW WHEREIN THE PROBABILITY THAT AN ANSWERING USER/EXPERT WILL RESPOND TO A QUESTION CORRESPONDS TO THE ANSWERING USERS HAVING RESPONSE RATES THAT ARE BASED ON THE TIME OF DAY

Methods, systems and apparatus, including computer programs encoded on a computer storage medium, for receiving aggregate user data, the aggregate user data corresponding to response rate of one or more answering users responding to requests, processing the aggregate user data to generate one or more analytical models, each of the one or more analytical models providing a plurality probabilities that an average answering user will respond to a request, each probability of the plurality of probabilities corresponding to a particular time period during a day, receiving a request, determining a time corresponding to the request, identifying a plurality of answering users, processing the one or more analytical models based on the time to identify a sub-set of answering users of the plurality of answering users, and transmitting the request to each answering user of the sub-set of answering users.