I could spend hours pontificating, explaining and lecturing and still not explain the difference between a Type I error and a Type II error as simply and as effectively as the image above. A picture really can be worth a thousand words.
Credit where credit is due: the image can be found in
The Essential Guide to Effect Sizes – Paul D. Ellis
This succinct and jargon-free introduction to effect sizes gives students and researchers the tools they need to interpret the practical significance of their results.
… a useful (and readable) book that aims to equip the reader to be able to distinguish between statisically significant and practically significant results.