Advance your students from relative measurements to learning about standardized units with this lesson that teaches them about inches and feet by using common classroom objects. (education.com)
Because transit measurements are relative measurements stellar spectra cancels out — in the first order approximation: the difference of a spectrum taken before transit and during transit will provide the transmission spectrum of the exoplanet atmosphere. (distantearths.com)
Typical instrument - related relative measurement uncertainties as derived from previous experiments are less than ± 6 % (for 0.9 > Φf > 0.1)[31]. (journals.plos.org)