“Without data, you’re just another person with an opinion.” W. Edwards Deming. As quoted at https://www.goodreads.com/author/quotes/310261.W_Edwards_Deming.
Referring to anecdotal data: “That’s not an experiment you have there, that’s an experience.” Sir Ronald A. Fisher.
…when people assume that the Excel output is enough. I think of all the research papers in economics where the authors must have spent dozens of hours trying all sorts of different model specifications, dozens of hours writing and rewriting the prose of the article, . . . and 15 minutes making the graphs.” Andrew Gelman, quoted at http://andrewgelman.com/2009/04/22/more_on_data_vi/.