Practice Lap times

Hi Guys

Could any one explain about the lap time results that we are getting for example Lap:1.21.873(+0:00:475) . i am curious about the numbers in the brackets. Thanks

thats the driver error,.. means that would be more in it if the driver would driver perfect

The time in brackets is the time that was lost on the run due to driver mistakes. Your driver ran a 1:21.873, but an error-free lap would have been 1:21.398 (a difference of 0:00.475).

So in trying to understand these times, so long as the number in brackets isn't too high, then  the lowest lap time ought to be the best setup to use?

Thanks lot for explaining :)  its clear now 

But doesn't a high error mean the setup is fast but prone to inconsistency?

I am wondering what effects the lap times. Had a driver jump from 1:34 to 1:31 by changing the wing by 1 on a practice run. Started at all feels good so that was the only change I made over all 5 runs. All runs before (2) were 1:34 and all after were 1:31. Mistakes were similar (0.2-0.5) for all runs so not like they made a 3 second mistake on the 1:34 laps.

Weather didn't change, and my other driver who I did laps with first had all the laps as 1:31

EDIT: Just an extra note, my friend and I were comparing practice times. At Malaysia his laps were 1:31 and mine were 1:34 for all runs. At China mine were all 1:31 apart from the 2 at 1:34 and his were all 1:34. I thought at Malaysia it was just my drivers as they are slower than his, but for it to reverse at China it got me thinking.