Well, back in 2011 there was Google Page Rank. It was what all SEOers wanted. They wanted that good Page Rank. However, eventually Google made it secret, so other measurements came out like DA, PA from Moz.com and TR from Majestic.com. Who has looked at those? Anyway, for DA, at the least, I'm distrustful, because spam can rise the DA in some instances, making the measurement unreliable.