The phrase "relative basis" refers to comparing or measuring something in relation to something else. It means looking at a particular thing or situation in comparison to a specific reference point or context. Full definition
They also offer the possibility of connecting with potential relatives based on matches in your DNA to other users in their database. (scientificamerican.com)
Returns on relative basis are still generally better and that has led us to purchase some grocery - anchored centers for various portfolios. (nreionline.com)