Not sure if this is correct but I'm gonna say natural resource
Andersonville, officially known as Camp Sumter, held more prisoners at any given time than any other Confederate military prison; according to the Civil War Trust, more than 45,000 Union soldiers were confined there, and 13,000 died from disease, poor sanitation, malnutrition, overcrowding, or exposure.
The proportion of subjects in the study that were randomly assigned to take St. John's wort is about 1/3 or one third. [113 / 338 = 0.334] 0.334 is equivalent to about 1/3.
This value makes sense because the study has 3 treatments, therefore, about 1/3 should be assigned.