Service Strategy consideration (utility / warranty)

glock77

Hi,

At the moment I am preparing to ITIL SOA exam and while reading Service Strategy I came across problem with understanding of utility / warranty.

In publication there is a graph which presents relation between utility / warranty (page: 63)


I understand the relation between them but I do not understand how this graph works. I mean:

1. What is on x / y axis and what single point of graph means
2. What is the interpretation of "Mean 1" and "Mean 2" points

Thanks for help.

glock77

Ok, solved - I was out of logical thinking and did not realize it is standard deviation