Discussion of AnneTheAgile's comment: Great introduction to get intuition. See: 1.Figure 3: Normal and non-Normal distributions with effect-size = 1; 2.Table II: Examples of average effect sizes from research (example: Students' test performance in reading 0.30). (I wish we had more categories than Rigor/Coolness/Novelty. This comment perhaps isn't exactly about 'rigor'.)