The biggest problem with the 5 whys is that the whole concept is taken out of context. In a manufacturing context every repeatable problem is a problem with your process. So in that context it makes a lot of sense to search for a process change that resolves your problem.
Let's say you make light bulbs, and every fifth bulb comes out misshapen. You would use the 5 whys to trace it back to the molding station, where you discover that bulbs cool at a different rate in one of the machines because the mold uses a better insulator. You could stop there and replace the insulator. But if your job is to increase yield, then you can save the company a lot of future money if you figure out how that mold got there in the first place. You might find that purchasing subbed a cheaper replacement based on an incomplete spec. Or you might find that the supplier recently switched materials.
The point is that when you're trying to establish a controlled, repeatable process, you need to understand where your controls break down.
Once you understand the process problem, then you make a business decision about what to change. It was never meant to be applied to R&D problems. R&D processes are not as concerned with repeatedly doing something correctly. They're concerned with making sure something can be done in the first place. It's a different class of problem.
Let's say you make light bulbs, and every fifth bulb comes out misshapen. You would use the 5 whys to trace it back to the molding station, where you discover that bulbs cool at a different rate in one of the machines because the mold uses a better insulator. You could stop there and replace the insulator. But if your job is to increase yield, then you can save the company a lot of future money if you figure out how that mold got there in the first place. You might find that purchasing subbed a cheaper replacement based on an incomplete spec. Or you might find that the supplier recently switched materials.
The point is that when you're trying to establish a controlled, repeatable process, you need to understand where your controls break down.
Once you understand the process problem, then you make a business decision about what to change. It was never meant to be applied to R&D problems. R&D processes are not as concerned with repeatedly doing something correctly. They're concerned with making sure something can be done in the first place. It's a different class of problem.