Well I think to large extent marketing firms rely on their own know-how, which I imagine is rather scientific. I have first hand experience with this (I am selling a computer game through Steam). Various statistics is used to see what does better. Their marketing people are really great at e.g. picking the most-clickable banner design, versus the one that I thought would be the most clickable (I did my own stats and confirmed their choice).
Well I think to large extent marketing firms rely on their own know-how, which I imagine is rather scientific. I have first hand experience with this (I am selling a computer game through Steam). Various statistics is used to see what does better. Their marketing people are really great at e.g. picking the most-clickable banner design, versus the one that I thought would be the most clickable (I did my own stats and confirmed their choice).