That's because a lot of VoIP services out there go by their product names and don't make a lot of noise about it. (That's not a big deal and they're not trying to hide it. For example, if you've heard of Skype, you've heard of one of the best-known Web-based VoIP services in use.
The Range Rule. The range rule tells us that the standard deviation of a sample is approximately equal to one fourth of the range of the data. In other words s = (Maximum â Minimum)/4.This is a very straightforward formula to use, and should only be used as a very rough estimate of the standard deviation.he Range Rule. The range rule tells us that the standard deviation of a sample is approximately equal to one fourth of the range of the data. In other words s = (Maximum â Minimum)/4.
Your calculator does not find the sample variance directly. You find the sample standard deviation and square it. Find the sample standard deviation: STAT; Arrow over to CALC; Choose 1:1-Var Stats (the default) ENTER; ENTER; Arrow down to find Sx; Find the sample variance: VARS; Choose 5:Statistics; Arrow down to Sx; ENTER puts it on the main screen