bathtub effect
n.— «Of particular urgency to Conrad and Michel is how best to address the scheduled downsizing of the bases’ personnel and mission before the Predator and Global Hawk UAVs are scheduled to arrive in 2009. The “bathtub” effect—as the downsizing is called—will be most evident when the last fueling tankers leave the base and before the next generation of tankers arrives, currently projected for 2012.» —“Conrad, new GFAFB chief talk future missions; tankers UAVs on table” Grand Forks Herald (North Dakota) Aug. 4, 2008. (source: Double-Tongued Dictionary)
Back in the late ’70s/early ’80s HQ Strategic Air Command’s strategic analysis section produced a chart of the relative strength of US vs USSR strategic forces over time which ‘someone’ said looked like an old, claw-foot bathtub….that is, it started high on the left and fell down quickly, then kind’a leveled out (down low) and rose again on the right (due to projected/desired force build up). It became known in strategic circles as “The bathtub chart.” and folks in and out of government talked about the need to “fill the bathtub” (with B-1s, B-2s, and modernized land and sub-based ballistic missiles. I _believe_ that to be the roots of using ‘bathtub’ in describing this downsizing of military capability. [I was there, in that strategic analysis shop.]
I have never heard “bathtub effect”, but a “bathtub curve” or “bathtub chart” is very well known to reliability engineers. It claims to show the failure rate w.r.t. time of a large number of identical items, operating under identical conditions. Initially, the failure rate is high as the weaklings perish, but falls gradually; next failure rate remains constant; finally, old age creeps up and the failure rate rises again. The “bathtub curve” falls in the category of “lies for little children”: the real world is nothing like it!