Orright, kiddies,
Everyone except for Bladeangle
If you are using the almost non-existant old CASA flight manuals (ie. the typewritten, tell you next to nothing, kept in a crappy old A5 folder type which CASA has been gradually phasing out totally), then they will say that they include the factor (which may be in excess of 1.15 if the aircraft has a heavy enough MTOW).
If there is a page at the start of the flight manual that shows the factory manual is the approved flight manual (which should be just about anything from the late seventies onwards by now unless your school is stuck in the stone age) then the factory figures (without any factor) are the figures to be used.
6.3 Where there is an approved foreign flight manual or a manufacturer’s data manual for an aeroplane that sets out the take-off distance required for that aeroplane, then that aeroplane must be operated so as to comply with either the requirements set out in paragraphs 6.1 and 6.2 or the requirements relating to take-off distance set out in either of those manuals.
Note: The data contained in some manufacturers’ data manuals is unfactored and makes no allowance for degraded aircraft performance. Where there is a considerable difference between the data in a manufacturer’s data manual and the data in the flight manual for the aeroplane then the manufacturer’s data should be treated with caution.
Once again a case of flying schools completely out of touch with the real world.
If you tell your CP that your Caravan won't be going to a strip because you don't have the CASA safety factor, they may not be very impressed.
And before everyone starts jumping on the "but those figures are obtained by a brand new aircraft with a test pilot" bandwagon, here's another myth gone...
FAR 23.45 (one of the rules FAA aircraft are certified under)
These procedures must be able to be executed consistently by pilots of average skill in atmospheric conditions reasonably expected to be encountered in service.