Hi there. First time poster, and Statistical newbie. I am trying to wrap my head around an idea for monitoring monthly real estate data.

Here is the issue:

I am running # of homes listed vs # of homes sold for a 12 month period.

However, with real estate, when you list your home for sale, it takes time, could be days, or months until the home sells and goes to a closing table.

So here is the thing. Lets say I pull data for January 1st - January 31st for a particular Zip Code..

Lets say Zip Code A has 20 Listed homes, and 25 Sold homes. On paper, it would look like this market is on fire. More homes sold than listed!? Wow, how is that possible.

Obviously, there is a delay in the market. While 20 new home owners have indeed listed their home, the 25 sold homes are usually and most likely homes that have listed the previous year.

Lets say they listed their home in October 2015. And they Closed January 2016...this is going to skew my data.

So if I report this data on Zip Code A, it looks like a healthy market to start the year, but obviously , it is not accurate.

So my question is, what/how, should I build my statistical table to monitor yearly stats that are accurate when dealing with delayed market numbers?

I thought of doing a "fiscal" or "seasonal type year, going from Mar 2015 - Feb 2016, but here is the problem.

If I stick to a 12 month cycle, the homes that eventually sell after 12 months, in month 13, 14, 15, will never be registered, because after the 12th month, I am resetting the query.

So in other words. Homes Listed between Jan 1st and Dec 31st wont always close in the 12 months. Meaning, homes listed in Oct or Nov lets say, dont close until March of the next year. So when I pull the new year for January, I am eliminating this data, which again skews my numbers.

I am a newbie to stats and excel, but have an idea on what I am doing.

So how to I pull my data for the best accuracy and reading of the local market?