In a single sentence the moral is: admit that complexity always increases, first from the model you fit to the data, thence to the model you use to think about and plan about the experiment and its analysis, and thence to the true situation.
John TukeyFar better an approximate answer to the right question, which is often vague, than the exact answer to the wrong question, which can always be made precise.
John TukeyThe greatest value of a picture is when it forces us to notice what we never expected to see.
John TukeyAll we know about the world teaches us that the effects of A and B are always different-in some decimal place-for any A and B. Thus asking "are the effects different?" is foolish.
John Tukey