# How do we know which transformation is occurring with blue/white screening?

MrGenetic
Books say 3 possibilities for this situation as insert within Lacz, insert outside Lacz, no inserted vectors, then these goes the transformation with Ecoli. But we can't know transformation yield %100. Thus, if we make blue white screening there is more possibilities.
Lacz-- inserted within white
Lacz-- inserted outside blue
Lacz-- no inserted blue
** No transformation white** ? ---> is this correct ? if it is correct, how we know the lacz inserted or not inserted clearly?