All "don't know" and "refused" are converted to null = missing.
SAS Scoring Code
array baka {*} digbak1a digbak2a digbak3a digbak4a digbak5a digbak6a;
array bakb {*} digbak1b digbak2b digbak3b digbak4b digbak5b digbak6b;
stop=0; scdb =0; i = 1;
do until (stop=1 or i = 7);
if max(baka{i},bakb{i}) = 1 then scdb = scdb + sum(baka{i},bakb{i}) ;
else if min(baka{i},bakb{i}) = 1 then scdb = scdb + 1;
else if baka{i}=8 and bakb{i}=8 then scdb = .;
else stop=1;
if baka{1} = . and bakb{1} = . then scdb = .;
i = i + 1;
end;
Score for Digits Backwards = scdb;