Time To Interactive reliability

[cpk]

In our company we would like to start publicizing the TimeToInteractive metric that we gather from regular test runs on our private instance. The issue I have is that the metric is not generated consistently. Some pages have more success than others but all have some level of missing data. My questions are if there is anything I can do test-wise to increase the odds of getting the TTI number and is there any back end work being done in this area to increase the reliability? I don't want to start evangelizing this metric only to have to face questions from frustrated page owners.