Two-Road Agreement

Two-road agreement is the state of two estimates of the same quantity, built on different main input sources, landing within 3 times of each other. A two-road conclusion on this site needs it to be rated Seeing: hazy or better. A single step can still be hazy without a second road, for the reasons listed under How We Rate a Reading.

The term is this site's own, and so is the factor of 3. It is a convention, not a statistical test.

Limits of the term

Agreement shows that two roads are consistent. It does not rule out a bias they share, so the page has to write out the assumptions common to both.

Two roads are not more reliable than one just for being two. A good first-hand measurement can be cited at its own precision and rated clear without any second road.

Missing the mark is reported too. On the Fermi paradox page the two roads land at least 3.3 times apart, so that page does not claim agreement and rates the crossing time overcast. See How We Rate a Reading.