Thresholds of persons known to be diabetic
   n = 15                         mean                   SD
  protan threshold          7.67                 4.36
  tritan threshold          21.47                14.53
Thresholds of persons known to suffer from
systemic hypertension
 n = 26                         mean                   SD
protan threshold          7.68                 6.78
tritan threshold          15.82                 5.52