Thus, for example, if the volume in the first quintile were to double, total cost would increase by 29 percent.
If the first quintile's volume were to double, cost would only go up by 5 percent. 
mnli hypothesis: If the first quintile's volume were to double, cost would only go up by 5 percent.  premise: Thus, for example, if the volume in the first quintile were to double, total cost would increase by 29 percent.