Some editors spend their careers trying to avoid their readers, either as individuals, when they call to make a complaint, or in the mass, for instance at a 'reader event'. But even those editors will have somewhere, whether in their minds or on a piece of paper, an image of the reader for whom they are creating the magazine.
A detailed understanding of the readership is the central element of the magazine's marketing strategy. As editor you must 'know your readers'. The presence of an identifiable reader, or rather body of readers, in any publishing relationship is the first essential for the creation of genuine editorial material. If the presence or absence of readers is entirely irrelevant to the success or failure of your efforts, you are not really an editor, except in the most narrow technical sense of someone who prepares words and pictures.
If you are editing an existing magazine, you have plenty of opportunity to encounter your readers. Are they, for instance, to be judged by the vociferous minority who contribute to the letters page? Are they the people you see on the bus, reading your magazine? Or are they the people you meet at trade shows?
Actually, they're all those people, but they are many more people besides, whose presence you can only perceive with a combination of hard fact and instinct. On the one hand, you have the statistics of your readership. On the other, you have your own feelings about the magazine's 'character' and appeal.
The figures you need are obvious enough: how many readers (and how many non-readers in the same market segment); their ages, sex and marital status; their social class; their location; their disposable income; their employment status; their domiciliary status, etc. If you are producing a professional magazine, you need details about their working lives: what exactly they do, how long they've been doing it, whom they work for, where they stand on the professional ladder.
This is essential background material, but you also need to know about their activity in the magazine market: which magazines they buy, which they