It is unrealistic to assume that one intervention will work for everyone.

The intervention worked, and prices have returned to their earlier range.

But the intervention has not worked, and for reasons that (after the fact) seem obvious.

Political interventions can also work according to different time scales.

Such intervention, by itself, cannot work for long if the markets want to push the other way.

To the surprise of many in the international community, our intervention worked.

The intervention by government officials worked, and a new contract reached on February 1.

For the time being at least, the coordinated intervention worked.

Another is that even if intervention had worked smoothly, there would have been serious complications and costs.

Rather, we should ask them: How do you know that your intervention works?