Our data at Codealike (
https://codealike.com) supports the conclusions. When we cross-reference other sources of data like ALM data in our field studies we find that the ratio between actual coding vs. perceptual time (the time we think it took to solve an issue) there is at least a 1.5x multiplier, no matter the team size or the team skills.
Beware though, the multiplier will change based on team size and skill, but will always be higher :)