Mobile Internet QoS KPI correlation

[yelcyn2]

Hi,
I'm writing a doc about QoS KPI correlation, that means I have to find relations between KPI, e.g. PDP_context_acctivation_succ_rate depends on DNS_response_succ_rate, or HTTP_page_download_time depends on DNS_response_time, etc...
after it i have to find possible network failures to be due from these metrics.

I can't find on the Forum and on The Internet any document about this correlations,
If you know about something, which could help me, please share...