Availability Index is LOW or Zero during non peak hours

We have few servers which are having very low or zero availability index even during the night time. Please advise what steps can be taken and how can we run few checks to see if server is responding fine.

Subject: calculation of availability index

I am not dismissing your problem by saying this: You should very carefully read the domino admin help on availability index.

This is a very complex calculation, it can easily be misleading in very small domains, servers with a very short collection periods, or with underutilized servers. In addition, the expansion factor can be modified on the server to use this information appropriately for workload balancing.