Hi - i don't use blogger, but generally my policy for image alt text is to make the alt text relevant to the article that I'm embedding the image into.  For instance, if I wrote an article about backpacks to consider buying for a trek to the Himalayas, I would probably mention the brand name of the backpack, and that it was for a Himalayas trek.

I don't recall seeing any kind of rule about how long to make the alt text, but based on my usage, my alt texts tend to be between 2 words to a sentence.

Another thing to consider about is that, you're trying to describe why you're using a certain image on the blog you've just posted.  So in that regard, you could use the same exact image on different posts on your site, but use completely different alt text.  Maybe the first post was about a trek to the Himalayas, while the second post was about how to choose a rugged backpack.  In each case, you might want to draw out different characteristics of the backpack, and thus write a different alt text to match the page.

Hi Georg, That's a huge decline, isn't it? But how about your conversion? If the decline did not cause a big impact to your ROI then I think there is nothing to worry that much. If it did, then there is really something wrong going on.

What I would recommend is that you review you Google Analytics (or any other analytics tool you are using) and determine which particular pages got the biggest declines (you can run the comparison feature of GA - like this month vs. last month) and try to check if these pages are still indexed on Google, try to check also if these pages still rank on your targeted keywords. Then do what is necessary to bounce back.

Regards,

Roy