nagi Algorithm

All "don't know" and "refused" are converted to null = missing.
All the items must be answered to compute the Nagi score.

if (q4fs, q5fs, q6fs, q7fs, q8fs) in (3 4 5) {
      nagi = 0;
      nagi = (q4fs ≥ 3 ) + (q5fs ≥ 3) + (q6fs ≥ 3) + (q7fs ≥ 3) + (q8fs ≥ 3);
      }

Each logical truth counts as +1.