How does Traffic Travis determine KW difficulty?

I've been using Traffic Travis for a little while, in part because I can get by with the free version. One thing that's always baffled me though is how it decides whether a KW is hard or easy to rank for. I take a look at the report for a keyword that is easy vs. medium, and sometimes it doesn't look like there's much difference. In some cases, the one with medium difficulty seems to have pages with less authority, fewer backlinks, and less optimization. Is there more that Traffic Travis is doing behind the scenes? Am I looking at the wrong stats? Or should I just trust my gut?

From the PR, Age, Amount of links, On site (Title, description, tags).

Nothing really extra-ordinary, just common sense.

I guess that's why I'm confused. If it's just common sense stuff, then why is it conflicting with my own common sense? Either my ability to judge difficulty is off (quite possible), or something in its formula is prone to error under certain circumstances.

I suppose in cases like this, I'll just overrule TT and learn from the experience if I end up making a bad call.

john1444 said:

From the PR, Age, Amount of links, On site (Title, description, tags).

Nothing really extra-ordinary, just common sense.

Click to expand...

Is the TT keyword difficulty lvl actually accurate or is it not?Any good tools that have accurate average seo competition analyzer?