After nine years as a transaction coordinator, I’ve seen enough Comparative Market Analyses (CMAs) to fill a small library. I’ve seen agents pull data from three blocks away and I’ve seen them pull data from three zip codes away because they couldn't find a "clean" match. I’ve watched seasoned pros price homes to the dollar, and I’ve watched rookie agents throw a number at the wall to see if it sticks.
One thing stays constant: the obsession with "market value." Homeowners want an answer, agents want a listing, and buyers want a deal. But as someone who spent years reading appraisal notes and seeing deals collapse because of inflated expectations, I have to ask: What would make this number wrong?
If you are trying to determine what your home is actually worth, we need to move past the fluff. We need to talk about data windows, specifically the difference between sold comps 90 days and sold comps 180 days. If your agent isn't giving you a range with an explanation of why that range might be wrong, you aren't getting a valuation—you’re getting a sales pitch.
What is a CMA, and Why Should You Care?
A Comparative Market Analysis (CMA) is not a magic crystal ball. It is a logic exercise. Its purpose is to demonstrate, through recent comparable sales, where a buyer—not a seller or an agent—would likely place their offer based on the current supply of competing homes.
A professional CMA considers:
- The Physical State: The floor plan, the condition of the roof, and the "curb appeal" (or lack thereof). Market Velocity: How fast the days-on-market (DOM) are accumulating. Location-Specific Micro-Markets: In the Albany and Capital Region markets, moving just two miles can mean the difference between a neighborhood with a high demand for school districts and a neighborhood that struggles to attract commuters.
If an agent creates a CMA without walking your property, ignore the report. They are guessing based on public records that are often outdated or incorrect. Public records don't know that you renovated your kitchen in 2022; they only know you bought the house in 2010.
The Battle of the Estimates: Algorithm vs. Reality
We need to address the elephant in the room: Zestimates and other online "automated valuation models" (AVMs). These algorithms are great for seeing broad trends, but they are notoriously blind to the "what would make this wrong" factor.
Algorithms cannot see that your neighbor’s home sold for $400k, but that neighbor had an in-ground pool and a finished basement while you have an overgrown backyard and a crawlspace. When you see a Zestimate, remember that it is an estimate of a mathematical trend, not the reality of your specific transaction. An agent’s CMA, when done properly, accounts for these nuances. An algorithm treats every house like a commodity; a skilled agent treats a house like an asset with individual quirks.
CMA vs. Paid Appraisal: The Difference in Stakes
People often confuse a CMA with a formal appraisal. They are not the same thing. The stakes, the costs, and the level of scrutiny are vastly different.
Feature Real Estate Agent CMA Paid Professional Appraisal Purpose Pricing strategy & marketing Lending & risk assessment Cost Usually free (part of the commission model) $450 – $800+ (out of pocket) Timing Hours or a few days 1 – 3 weeks Depth Broad look at market positioning Deep dive into site-specific utilityIf your deal is contingent on financing, the appraiser’s word is final. They don't care about your "emotional value." They care about recent comparable sales that prove the value of your home to a bank. If you are priced 10% above the range dictated by 180-day comps, the deal will likely crash the moment the bank’s appraiser visits.
The 90-vs-180-Day Debate: How Recent Should Comps Be?
This is where the debate heats up. Everyone wants the most current data, but the most current data is not always the most representative data.
The Case for Sold Comps 90 Days
In a volatile or fast-moving market, 90 days is the gold standard. If you are selling in a suburban hub where inventory is low and competition is high, looking back 180 days is like looking at a different economy. You want sold comps last 90 days to see how the market reacted to current interest rates, current gas prices, and current school district cycles. If you use sold comps 90 days old, you are getting the closest representation of what a buyer is willing to write a check for today.
The Case for Sold Comps 180 Days
Sometimes, 90 days just doesn't offer enough data. If your home is in a rural area or a quiet niche market, you might only have two sales within 90 days. That’s not a sample size; that’s a coincidence. Extending the window to sold comps 180 days provides the "meat" needed for a statistically significant report. It smooths out the peaks and valleys of a slow market. However, you must adjust these older sales for market shifts that have occurred in the interim.
The Selection Logic: Distance and Recency
When selecting comps, I look for a "tight band." If I’m pulling data, I start with the "Rule of Three":
Proximity: Keep it as close as humanly possible. If a house sold two streets over, that is your primary indicator. Recency: Start at 90 days. If the data is dry, move to 180 days. Utility: Does the house "function" the same way? A 3-bedroom, 2-bath ranch is not a direct comp for a 3-bedroom, 1-bath colonial, regardless of how close they are.What would make this number wrong? Ignoring the "Days on Market" (DOM) for those comps. If a comp sold in 90 days but sat on the market for 180, it is not a "hot market" sale. It was a home that needed a price reduction. If your agent is showing you comps that sold quickly but doesn't mention that the sellers paid $10,000 in closing costs, they are inflating the value. Always ask: "Did the seller contribute to the buyer’s closing costs?" If so, that needs to be subtracted from the sale price to get the true market value.
Final Thoughts: Don't Fall for the "Market is Hot" Vague-ism
If an agent tells you the "market is hot" without showing you a table of recent comparable sales, show them the door. A "hot market" is a buzzword used to justify lazy pricing. Precision is the antidote to the anxiety of a real estate transaction.
When reviewing your next CMA, demand to see the range. If they say your house is worth $450,000, ask them for the low and the high. A proper range would look something like $440,000 to $460,000. Anything outside of that range is where you need to start digging into the condition of the homes compared to your own.
Don't be afraid to challenge the numbers. It’s your home, your equity, and your future. If the numbers don't add up, ask the hard question: "What would make this number wrong?" If your agent gets defensive, you have your answer—they aren't looking at the worth of a professional cma data, they’re just looking at the clock.