A CMA, comparable market analysis, is a way to determine the current market value of a home.  It's how an agent determines the price for which a home will sell.  Good listing agents do these before advising a seller to list price.  Likewise, good buyers agents do these before advising a buyer what to offer.

Market value is determined by taking the last 60 to 90 days worth of sales that are in the same neighborhood and most like the house in question (subject).  Then you adjust for differences between the subject and those that sold.  If a home that sold has two more bedrooms and more square footage than the subject, a deduction in price is made to that larger home that sold.  If the subject has a finished basement, and a home that sold doesn't, you would add the price of that finished basement to the home that sold.  Adjustments like these are how you come to market value.

When making adjustments, you don't take small items into account like ceiling fans.  You take large items like number of bedrooms, bathrooms, fireplaces, decks, fences, etc into account.  Upgrades like granite and newer appliances should also be taken into account when doing a CMA.

A CMA is more of an art than a science.  However, doing a CMA before lisitng your home, or making an offer on one, will tell you the market value of a home.  Make sure the agent you hire is doing a CMA before advising you on listing or offer price.