WASHINGTON (CNN) -- We know that conventions and primaries often produce a "bounce" that boosts a president's approval rating by several points. Does the State of the Union message have the same effect?

Apparently not. Since 1952, Presidents have lost about half a percentage point, on average, from their approval ratings after State of the Union speeches. Approval ratings went up after 17 addresses and down after 25 of them. The approval rating remained unchanged after three addresses.

Since 1977, newly-inaugurated presidents have given speeches that technically don't count as State of the Union addresses but were treated as such by Congress and the media -- joint sessions meeting in the House chamber, prime-time coverage with all the network anchors, the whole shebang. With one exception, the public loved these events. They gave a new president his first chance to look presidential and tended to reassure Americans that they had not made the wrong choice. Reagan's approval rating grew five points after his first speech in 1981; Clinton got an eight-point boost in 1993 and the elder George Bush saw his approval rating zoom up 12 points in 1989.

But there is still no bounce even if you toss in those pseudo-State-of-the-Union addresses. The average change in the approval rating is a drop of 0.02 percentage points. No bounce there.