To what do we owe the tame 2 percent annualized increase in the core CPI in the fourth quarter? Why, our old friend, owners equivalent rent: the largest single component of the CPI -- 23.4 percent of the CPI and almost 29.8 percent of the core index -- and one that imputes a rental value to owner-occupied homes based on a survey of rental units. No Prices = Bad Data In other words, ``the only thing holding inflation down is the one thing we don't measure directly,'' says Joe Carson, director of economic research at Alliance Bernstein.