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Every year, at least one student shows up at my door, holds out an open notebook with a page full of numbers, and says, ‘I’ve collected all this data⁹ and now I don’t know what to do with it’. I strongly resist the temptation to tell them to go away, or to ask why they didn’t come to see me months ago. I usher them in and see what we can salvage. Usually, it is a debacle. The data collected are not suitable for testing the hypothesis; their sample is poorly defined; they don’t have enough of the right types of observations; they have used different methods for collecting data at baseline and follow‐up; the list goes on and on.

Box 1.3 summarizes the steps that should be undertaken when conducting research. Although Steps 1 and 2 are essential (‘Getting the question right’), probably the most important step is Step 3, the point at which you design the research project. It is vital at this stage that you consult a statistician (as well as others who have done similar research). Be prepared to accept that your hypothesis may need modifying, and that the design that you first thought of is not perfect and would benefit from improvements. It is very unlikely that you will have got it right at your first attempt. Be prepared to listen and to learn from your mistakes. As I said in the Introduction to this book, statisticians may be perceived as monstrous, inhuman creatures intent only on humiliating those who come to consult them. In reality, the statistician is there to advise you concerning the likelihood of being able to prove your hypothesis, guide you in the design of the study, the choice of measurements which you intend to make, and the type of analyses you plan to undertake. Months or years of effort can be wasted if you embark on a study which is flawed in its design. Do not take the chance! Be brave! Be thick‐skinned! Talk with statisticians and accept their advice. Even get a second opinion if you feel very uncertain about the advice you are given.