hedge ratio

can someone plz help me with this: is a hedge ratio the same thing as delta? im looking at an example where for mortgage renewals, they compare the renewal ratio with the hedge ratio. if the renewal is greater than we are underhedged, but if the hedge ratio is greater we are overhedged. so im thinking the renewal ratio is the percentage of balances on mortgages that were renewed on the renewal date, and the hedge ratio is the percentage of the balance that we wanted to hedge for, ie if we set the hedge ratio to 50% it means we only want to hedge for half of the volume and leave the other half unhedged. so we assume that only 50% will renew, and thus if more people actually renewed than we expected, we didn’t hedge enough. does this sound right what i just said, or if not, can someone plz elaborate? thanks!