FTP Test Indoors or Out

I am currently completing the at home lifting plan. I plan on starting the SS Part 1 plan in mid-February. Is doing the FTP test indoor or outdoor preferable? I would like to do a good mix of indoor and outdoor riding during the plan. Personally, I’d much prefer to do the test outdoors if possible.

Test outside if at all possible - in our experience coaching athletes and analyzing their power data, we see 2-5% more watts from outside compared to inside.

I touched on this in this podcast

Of course if outside is not possible, test indoors in order to FtFP