[randomvisitor]

> No variation of the gravitational constant is discernible, (dG/dt) / G = (0.0±1.1)x10–12 /yr

If we're obsessing over details, I'm wondering if 0.0 is indeed the center of the confidence interval, or if this is just a way to say they have bounded |G'/G|. The cited paper ("Lunar laser tests of gravitational physics") just states the result without giving much detail.

[ISL]

In general, because G' is a signed quantity, I would expect any experiment to be quoting double-sided errorbars. If G increases, one thing happens, if G decreases, the opposite happens, so the difference is discernable.

I'd take 0.0 to be their reported central value.