This test goes hand in hand with the original title test performed, except now were testing how Google, Yahoo and MSN interpret the use of the <description> and <keywords> tags for affects.
The planned affects will vary, as the test is not set to find just one particular instance of affect, but more how it interprets the use of the tags in conjunction together, searching terms in various orders and so forth. A further test will be done to the side of this, which will be for some low key phrase actually being searched for within the engines, to determine the ranking affects of the title, description and keywords (if any) ranking affects.
I don't expect to see anything come from the keywords tags, as the search engines themselves have said they no longer use it, but that's what this will confirm for archival purposes. The keywords tag is actually different from the title and description, containing rubbish that nobody would search. If the page picks up in any of the three engines from that tag, then it does use it to some extent, otherwise, nothing.
The use of the tags by themselves and in conjunction together (mainly the title & description) do significantly change the way in which your rankings will be achieved. In the body of this page for example, the terms used within the three tags, which are all identical, are not listed here. So this will not have any affect on how each engine uses the description they choose to display within their results. As you are most likely thinking now, this test opens up various aspects that must all be tested, some stumbled upon no doubt and other factors.
What I expect to find is this:
