Every month in this space I give you the statistics on what the market is doing in Culpeper, Fauquier, Rappahannock and Prince William counties. (With Warren thrown in occasionally!)

What I haven't really talked about is where this data comes from and what inherent flaws there might be in this data. It now seems like I'm overdue for that discussion.

Each month the data I use as the basis for my analysis comes from the Multiple Listing Service (MLS). The MLS that serves our area is called MRIS. The data in this system comes from what the agents input. They input their listings and they input the information when it gets sold.

So, here's the first weakness in the system, the human factor. People forget, get lazy, get busy, etc. It's the same problem with every system, anywhere, run by people!

There are brokerages that still don't list properties in the MLS. They are few and far between, but a few of them still exist. (By the way, if you really don't want your house to get sold, just keep it out of the MLS!)

Builders generally don't list every house they have for sale in the MLS. They'll list, perhaps, one of each model they have. So the MLS always understates the total inventory and seriously understates new construction inventory.

While many For Sale By Owner (FSBO) properties are now in the MLS, many more are still not, relying on the handwritten sign in the yard. Again, this understates inventory.

But for whatever flaws there are, the MLS is the best system we've got. It's as close as I can get to getting a total snapshot of the market at any given time.

A CMA is a Comparable Market Analysis. I've also seen it called Competitive Market Analysis. Regardless of how you define it, it's purpose is to give a potential seller an idea about what their home will sell for.

Many real estate agents routinely offer to do a free CMA as a way of getting their foot in the door with a potential client. And, a CMA can be a very valuable tool for the seller. But I don't believe most sellers have enough information to accurately determine if what they're looking at makes sense.

You've probably heard the quote about "lies, damned lies, and statistics".  Well, then there are CMAs.

I can get a CMA to say just about anything I want it to. But a proper CMA, while not an actual appraisal, should take into account the methods an appraiser will use when choosing which homes to use as comparisons for yours.

First of all, if you live in a good sized subdivision and there have been recent sales, that's what will be used. It doesn't matter if you think the people down the road don't have as nice a house. The rules that appraisers follow will almost guarantee that the most important comparables he or she will look at will be in the subdivision where you live.

And, they're only going to look at recent sales. In this market, if it sold more than six months ago it's insane to consider it as a guide to pricing your home. No appraiser worth their salt will use it. Prices in this market may have stabilized. But there's also a pretty good chance they're still dropping.  The more current comparables you have, the better.

The comparables used should be as close to your home as possible in terms of age, style, number of rooms, garage, lot size, etc. Think apples to apples!

And the comparables should be focused on what has sold, not what's active. It doesn't matter what someone asks for their house. It only matters what they can actually sell it for!

CMAs can be manipulated to pull the data that supports the price a seller wants. And there are plenty of agents who want or need business badly enough to tell a seller what they want to hear. That's a disservice to everyone in the long run!

So push back and ask the hard questions when you look at the numbers. If you think those numbers look too good to be true, you're probably right!