New Relic Alert Policy with Both Apdex & Error Threshold

Question

What are the scenarios to configure both Apdex & error threshold alert policies in New Relic alert policies configuration?

Looks like both of them are correlated, when the error number raise, the Apdex getting lower and vice versa.

I'm familiar with Apdex defenition and the fact that it's an industry standard to measure users' satisfaction with the response time of web applications and services:

Answer 1

Scenarios where satisfied formula is not in direct connection to error, for example:

You can define that if response time more than 1 seconds it's not satisfied but tolerant request which can be up to 10 seconds.

Now if you define by error rate only you won't find that server response was average of 8 seconds which you don't consider ok.

If you define by Apdex only - only one or few errors almost won't effect the Apdex score.

So in case you are intolerant for errors and you want also to check a good Apdex score you can set the score you want and allow 0 (or a few) errors simultaneously.