In statistics we have some odd rule of thumbs, despite evidence that does little to support it. All our classic texts say that if we have a sufficient sample size then we can make assumptions about the distribution of the sample mean based on the Central Limit Theorem. In cases that involve the t-distribution, if n ≥ 30 then we can apply the CLT and use the z-value instead of the t-value, and yet the t-value for any given significance level is still pretty far from the respec