I have a site (http://www.uogateway.com/index.php) where people can submit their UO servers and it acts as a top site list. There's a also a poller that runs in the background and gathers statistics on their server such as the network response time taken to send a packet. Each time it polls, it writes an entry to the DB, and then generates the new graph.

The way the graph works is that the scale is set to 0-max where max is the biggest number in that set of stats. Now my issue is, if one value is super high (ex: a lag spike) it will skew the rest of the stats. For example if it averages at 150-200ms that gives a decent graphing range, but if I get one sample that hits like 50000ms then it makes the 150-200 just a small line.

What is the best way to prevent this?

You could either ignore any data that is above a certain value, or poll a second time if the first response took too long to be received.

I was thinking of just polling twice too, as when the number is completely abnormal it's usually a temp issue during that actual moment.