title: Neural Network: Handling unavailable inputs (missing or incomplete data)
body: <p>Hopefully the last NN question you'll get from me this weekend, but here goes :)</p>
  
  <p>Is there a way to handle an input that you "don't always know"... so it doesn't affect the weightings somehow?</p>
  
  <p>Soo... if I ask someone if they are male or female and they would not like to answer, is there a way to disregard this input? Perhaps by placing it squarely in the centre? (assuming 1,0 inputs at 0.5?)</p>
  
  <p>Thanks</p>