title: Probability distribution for sms answer delays
body: <p>I'm writing an app using sms as communication.
  I have chosen to subscribe to an sms-gateway, which provides me with an API for doing so.</p>
  
  <p>The API has functions for <em>sending</em> as well as <em>pulling</em> new messages. It does however not have any kind of <em>push</em> functionality.</p>
  
  <p>In order to do my queries most efficient, I'm seeking data on how long time people wait before they answer a text message - as a probability function.</p>
  
  <p>Extra info:</p>
  
  <ul>
  <li>The application is interactive (as can be), so I suppose the times will be pretty similar to real life human-human communication.</li>
  <li>I don't believe differences in personal style will play a big impact on the right times and frequencies to query, so average data should be fine.</li>
  </ul>
  
  <p><strong>Update</strong></p>
  
  <p>I'm impressed and honered by the many great answers recieved. I have concluded that my best shot will be a few adaptable heuristics, including exponential (or maybe polynomial) backoff.</p>
  
  <p>All along I will be gathering statistics for later analysis. Maybe something will show up. I think I will cheat start on the algorithm for generating poll-frquenzies from a probability distribution. That'll be fun.</p>
  
  <p>Thanks again many times.</p>