If I can have it open in a new tab I always do. That is for my own websites or sites like HubPages. I figure that the person may click on a link to view another article of mine, buy a product from my page, etc. but they may still want to come back and read the rest that is on the original page.
The longer you can keep the person on the website the better unless you are driving them to make a sale, but even then you can have it open in a new page and they can purchase the product. Then they may purchase, and click on a link to read the next hub in your series, find something else to click on or buy, etc.
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