After reading all the input, it appears that if turbulence imposes lift changes (ie vertical wind shear or horizontal turbulence which comes on the nose or tail) than its:
increase speed by 1% = increase bumps by 2%
If it is horizontal wind shear from 3 or 9 O'clock, than its linear as there is no lift change involved:
increase speed by 1% = increase bumps by 1%
Comments?