Why are there giant concrete tunnels in the desert?

I am wondering how the data picked up by these measuring tools is analyzed. If you are saying that the gravitational effects you are looking for are so small AND that the measuring devices are so prone to measurement error because of outside noise, the statistical power of whatever hypothesis test you are using to decide if the signal you're picking up is real or not must be quite low. I dont wanna be one of those skeptical ppl but i hope the physicists doint these analyses (unlike researchers in other fields) aren't manipulating their pvalues or hypothesis tests to report positive results (and therefore receive further funding).