As I've looked at the profiles of other members here, I've noticed the system gives a similarity percentage.  There are some who I expected to have a greater similarity to me because they seem to read the same genre of books, but they end up being like 36% similar to me.  However, there are others who, when I look at their reviews and books posted,  don't seem to have much in common with me, but yet they have like 55% similarity to me.  Is the similarity percentage based on wish list, reviews, books posted taken as a whole?  How exactly does the system come up with the percentage?  Just curious...

Yeah I noticed the same thing. It  must take into account  books you've posted.  I used to post a lot of WL books I found cheap somewhere and many were ones I'd never read myself. 

I've seen buddies of mine iwth almost an identical WL to me with a low similarity and others with a high similarity to me and I woujld have no interest in the books their wishing for at all. 

I don't really pay attention to the ratings.

Similarity Index

Introduced August, 2008.

The Similarity Index shows how "alike" you and your Friend are.  it is determined based on the information you provide to the club through your participation.  So when you apply star ratings to a book, add an item to your Wish List, or tell us what your favorite genres are, we're more able to come up with a profile of you as a reader.  And as others do the same, we can start matching up people who have similar tastes and habits.

Right now, the Similarity Index is visible only on your Friends and on another member's Profile, but we do anticipate expanding this in many fun ways in the future. 

To check your Similarity to a Friend, go to your Friends (in the menu under My Account at the top of any page on the site, or from Friends tab on the My Account main page).  You will see a notation --  Similarity: xx% -- to the right of each Friend's name.    The range of similarity is from 0% to 100%. 

Right now, most scores will be seem low.  This is because the Similarity Index is based on some club features that are still pretty young or under-used.  You can make your Similarity Index more powerful and accurate by applying Star ratings to every book you have read, and also choosing your favorite genres on the Member Homepage.   

When you find a highly similar Friend, you can

• check her bookshelf for books she has that you might be interested in
• check her Wish list for books she is interested in that you may want to Wish List too
• revel in the glorious feeling of not being alone...you are not the only one with your weirdo taste in books! :)

This is a fun feature whose results may surprise you!

Thanks for the comprehensive answer!

Like Mary, this is a feature I don't find particularly useful or accurate so I usually skip over it; as such, I have no idea how it works.

One of my friends consistently shows over 100% similarity to me.  Right now it's showing at 102%.  I've seen it show as high as 105%.  I guess she knows more about what I like to read than I do myself.  LOL