The 64% Question

     %Time ExclSec CumulS #Calls sec/call Csec/c  Name
      63.7   0.830  0.829    109   0.0076 0.0076  main::letter_histogram

I said "This is 64% of the remaining run time"
- Why 64% and not 63.7% ?
The total run time was about 1.22 CPU seconds
- The resolution of the measurements was only 0.01 second
- The resolution of the %Time column is therefore 0.81%
It's like announcing that "85.714% of surveyed respondents prefer Perl to Python"
- Sounds really precise
- But what you actually mean is "6 out of 7"
That 63.7% actually means "83 out of 122"
- Or perhaps "somewhere between 62.9 and 64.5%"
The percentages are reported with eight times more precision than the measurements actually have