I guess the numerator is number of incidents / failures to provide video. But what's the denominator? Days? Months? Years? Number of Cameras?
I was thinking just number of failed attempts/number of total attempts.
Though looking back at Bill's statement above, I guess I really was thinking of the guy who's system runs for months without any video review and then blam!, really needs it for LE purposes. So Carl's Six Sigma performance, though exemplary, is plausible because of the constant attempted retrieval and feedback, driving process improvements.
So I am thinking now that the critical slice for this question would be systems where there is no dedicated security infrastructure in place per se. Where the system was put in, 'just in case of', and often runs unattended for weeks at a time, continuously mulching old video as needed to make room for new... SOHO and a little bigger mainly.
With that in mind, I am thinking that most places like this probably need to have their installer help get video off the system for LE if needed. So a more precise question would be, what percent of the time that you need to extract video from a system for LE are you unable to because no recording was made, or a blank signal was recorded?
Or number of failed attempts/number of total attempts.