It may surprise you that the less certain you are about what you are measuring the more I would encourage you to try to measure what ever it is you're not sure about. It seems counter intuitive but the trouble with not being certain is making no measures at all. Then I can guarantee you won't be surprised by what happens. Because you had no expectations in the first place.You need to put a finger in the air. You need to test the water.

The reason for making an assumption or two and attaching a measure or two to them is that reality will be different. But your initial measures because they won't work the way you expected will shape your understanding of what happens. You will actually learn something.

Making predictions and measures and having to justify them at least to yourself is a great way to pull out the assumptions you are working with which no one will ever challenge because you have never articulated them. Set up a measure or two and you will be challenged and you will have to bring out your assumptions to defend yourself. That's why this is so valuable as an exercise. It forces you to make explicit what is implicit and inarticulate. That is hugely valuable. the more you do it the more likely you are to be trading on useful experiences - predictions which start to be borne out by the facts because you learned from experience. So don't be afraid to set a measure and justify your choice. You'll be doing everyone a favour. And you will be taking the first step towards getting valuable experience.