title: gpsd TPV json data has 95% conficence errors (ex: ept, epx, epy ...) How do you use the numbers?
body: <p><a href="https://i.stack.imgur.com/DtWBq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/DtWBq.png" alt="enter image description here"></a></p>
  
  <p><a href="http://www.catb.org/gpsd/gpsd_json.html" rel="nofollow noreferrer">http://www.catb.org/gpsd/gpsd_json.html</a></p>
  
  <p>Let's say I get </p>
  
  <ul>
  <li><code>"alt":1343.127</code></li>
  <li><code>"epv":32.321</code></li>
  </ul>
  
  <p>in TPV data.  </p>
  
  <p><code>epv</code> is "Estimated vertical error in meters, 95% confidence", so this means, at 95% of chance, the data has 32.321 meters differences in 1343.127(alt) meters from the actual altitude?</p>
  
  <p>Same question goes to other error values such as ept, epx, epy, epd ..</p>
  
  <ul>
  <li>ept for time</li>
  <li>epx for longitude</li>
  <li>epy for latitude</li>
  <li>epv for altitude</li>
  <li>epd for track (heading)??</li>
  <li>eps for speed</li>
  <li>epc for climb</li>
  </ul>