I think a distinction should be made for measurements and predictions. If you are measuring something then you have a scale, and you probably have a sense of th

I think a distinction should be made for measurements and predictions. If you are measuring something then you have a scale, and you probably have a sense of the margin of error. That is easy to translate into significant figures. When you make predictions, things are much harder. There is also the question of whether you should take the variance of the model into account, or its accuracy.