Wiep Knol did an interesting test in order to determine the value of an alt attribute, in comparison with a title tag and anchor text. It’s definitely worth reading it ! Thank you Wiep for sharing this great info!

Are image links valuable as regular text links?

Tests in the past, as well as experience, have showed that if you compare a text link with an optimized anchor text with an image link with the same words attached as alt attribute, the page where the anchor text link points to will rank higher. This means that there’s no need to determine if a text link is “better” than an image link, but it still is worth to test the differences and smaller factors underneath. Nothing big, but useful enough to run a test.

To read Wiep Knoll’s article, click here