Hi,
These things vary in the inductance they introduce and of course the capacitor value will change things a lot too depending on its value. The best you can do probably is to try to find out the manufacturers specs for the bead in question and take it from there.
You could try to measure the ripple before and after the bead. The wire lead connecting the circuit already has some inductance, the bead just increases the inductance of the wire, so you would test the same way you test an inductor and capacitor filter. It may be a small inductance however so it may only reduce the much higher harmonics and not actually affect the ripple itself too much unless the switching frequency is high. The reason for using them is often just to reduce RFI not to really help the ripple that much.