Value of Book Cover Design

Author services site Reedsy conduct a semi-scientific test into the relative marketing merits of a better designed cover. The signal seems pretty clear, though one would want to make such tests on a much larger scale to fully quantify the effectiveness. But of course there is a reason mainstream publishers invest a lot of effort into eye-catching genre-appropriate cover designs — it very much works, and catches the segment of the buying public interested in that specific kind of title.