My latest Bloomberg column asks why markets are obsessed with when the Federal Reserve will raise a key interest rate by a quarter point.

Is our economy really so fragile that such a modest change would be disruptive?
It’s unlikely that the direct effects would make a huge difference. But that’s not the whole story. The Fed doesn’t follow a simple rule in setting its policies. It doesn’t say, for example, that it will loosen policy whenever market expectations of average inflation rates over the next five years fall below 1.5 percent, and tighten whenever they rise above 2.5 percent. When it tells the world its intentions, it is deliberately opaque. That makes its conduct hard to predict, and puts a premium on evidence of its true goals.