Regarding a visitor adding an item to their shopping cart, I’m trying to find out which has been found to be most effective for sales conversion:
Should clicking on the ‘add to cart’ button take visitors to their shopping cart… or should it leave them on product pages?
Which is most effective? Have there been any studies done on this? Where could I find answers to questions like this?
Ideally I would test it for myself and compare results but in my low-sales-volume situation, it would take months to have enough data to reliably compare.
Thanks
If you have only one product I would change it from “add” to “buy”.
If you have more than one product, you wouldn’t mind if they bought only one because their shopping was interrupted?
How about when you click “Add to basket”, it pops up a light box giving users the option to ‘Go to checkout’ or ‘Continue shopping’? That is seamless because it doesn’t require a page load, and gives the user control of their destination. It also allows you to put up a confirmation message to say that the item has been successfully added without interrupting the work flow.
I have no research or anything, just thinking out loud here!
From a purely personal point of view, I prefer the kind of approach Stevie D suggests. Several sites I use display light boxes; one of these closes automatically after ten (I think) seconds, or it can be closed manually. Other sites use a sidebar to show the contents of the basket without taking you away from the page you are on.
Bottom line - I prefer not to be taken to the basket.
Ask your friends, family, colleagues - anybody you know who shops online, however infrequently. It won’t be scientific, but it will give you a rough idea of the views of real people. 
Test it with Google Analytics Content Experiments (for example) and you will have the answer. You really do not need a high traffic volume to do this.