There is no benchmark for invalid conclusions. True input may yield true output, but it may not. You cannot count of the fact that true premises will lead to a true conclusion. The concepts of validity and invalidity will later help us determine fallacious arguments. One can reach a conclusion through a process of deduction or induction.
Deduction is the process of deriving a conclusion that necessarily follows from a set of premises.
In a deductive argument, if all the premises are true, the conclusion must be true. All mammals are warm-blooded. Therefore, all cats are warm-blooded. Induction is the process of drawing a conclusion, or supposing based on past observation, that a particular hypothesis is true. Therefore all birds probably have feathers.