Galaxies follow a tight radial acceleration relation ( RAR ) : the acceleration observed at every radius correlates with that expected from the distribution of baryons .
We use the Markov chain Monte Carlo method to fit the mean RAR to 175 individual galaxies in the SPARC database , marginalizing over stellar mass-to-light ratio ( \Upsilon _ { \star } ) , galaxy distance , and disk inclination .
Acceptable fits with astrophysically reasonable parameters are found for the vast majority of galaxies .
The residuals around these fits have an rms scatter of only 0.057 dex ( \sim 13 \% ) .
This is in agreement with the predictions of modified Newtonian dynamics ( MOND ) .
We further consider a generalized version of the RAR that , unlike MOND , permits galaxy-to-galaxy variation in the critical acceleration scale .
The fits are not improved with this additional freedom : there is no credible indication of variation in the critical acceleration scale .
The data are consistent with the action of a single effective force law .
The apparent universality of the acceleration scale and the small residual scatter are key to understanding galaxies .