When thinking of launching any product, and that includes a self-published e-book, if is essential to have some idea as to who are the potential customers or, in this case, readers.

As an e-book is read on e-readers, it goes without saying those non-e-readers owners are automatically excluded from the potential readers. So, having a picture of the demographics of e-readers owner is a good place to start checking who the potential readers are.

A Nielsen Wire study published last week indicates that the demographics are changing.

The age group owning e-readers is evolving fast. Last third semester 2010, 62 percent of tablet owners were under the age of 34 and only 10 percent were over the age of 55. By the second semester 2011, only 46 percent of tablet owners were under the age of 34 and the percentage of those over 55 had increased to 19 percent.

Genderwise, the changes are also drastic and tilted towards women. Sixty-one percent of all e-Reader owners are now female, compared to a mere 46 percent in the third semester of 2010.

The low rate of penetration among teens indicates that publishing an ebook for YA without a print book equivalent will only have the potential to reach a relatively small target audience

The specific technical support used by the potential reader is also a relevant factor in estimating the existing potential readers’ pool. This is especially relevant when time is short to format and promote different formats.

For example, women seem to be increasingly found of e-readers, more than of tablets or smartphones.

This means for romance literature and chick lit for example, focusing more on e-readers might be a smart move.

Another interesting variable is the main activity by user while using a reading device.

For a writer like Declan Conner for example, whose series is entitled Lunch Break Thriller, it seems that smartphones would be the most used support to read his books, as it has a higher rate of use in waiting for something, with friends or family and commuting and the lowest one in lying in bed.

So getting to know your customers is also very relevant for writers who intend to rise to fame.