Hey William,

When you're looking at the time graphs, each pixel in the graph can be comprised of 1 or more samples. If you're looking at a smaller time frame (like 5 minutes), each sample may be multiple pixels wide. If you're viewing a larger timeframe (48 hours, for example), it gets tough to represent each sample on it's own pixel (as there's a limited amount of space to work with). PingPlotter starts to average the latencies when you zoom out to a larger timeframe to make an effort to get everything in view. We cover this concept in more detail here:

http://www.pingman.com/kb/20

Hopefully this helps explain things a little more clearly. If you should find yourself with any other questions, or needing any other assistance - please don't hesitate to email us at support@pingplotter.com. 

Cheers! 

-Phillip