Multiple studies have shown the efficacy of TM as an intervention for treating stress. One blind study by MacLean et al. (1997) took a random sample of men ranging in age from 18-32 and tested them in a laboratory setting for acute effects of a variety of stressful tasks. The stressors were mental arithmetic, mirror star-tracing, and isometric handgrip. Measurements of hormones were taken before intervention as a baseline and after participating in TM or stress education classes (SEC) for a total of four months (twice, daily). After running a t test and ANCOVA, researchers found that the TM group’s cortisol levels significantly decreased in both baseline and overall amounts and that cortisol response was markedly more sensitive for the posttest in comparison to the pretest (MacLean et al. 1997:381).