title: Google Analytics User-ID | Value for singed out users
body: <p>I integrated the Google Analytics User-ID feature on our website today (in combination with Google Tag Manager). It's working great for logged in users.</p>
  
  <p>I use the UID of our system for logged in users.</p>
  
  <p><a href="https://i.stack.imgur.com/MGI0O.png" rel="nofollow noreferrer">Logged in user example</a></p>
  
  <p>However, I am not sure which value has to be used for users that are <strong>not logged in.</strong></p>
  
  <p>Currently, it's just blank if the <code>userId</code> value can not be set because the user is not logged in yet.</p>
  
  <p><a href="https://i.stack.imgur.com/MFi99.png" rel="nofollow noreferrer">Logged out user example</a></p>
  
  <p>Is it okay if its just blank? Or do I have to set the value to something specific?</p>
  
  <p>I thought about:</p>
  
  <ul>
  <li>setting a Default Value for the Data Layer Variable for <code>userId</code> in the GTM</li>
  <li>using the <code>clientId</code> that is stored in the <code>_ga</code> cookie</li>
  </ul>
  
  <p>But I just don't know which what the correct thing to do is here. I can't find a clear answer to this online, and the Google Guides and Documentations don't expressively say anything about it either that I've seen.</p>
  
  <p>I would really appreciate any help with this. And thank you in advance for your suggestions and answers!</p>
  
  <p>Cheers!</p>