Data Methodology for Current Market Trends Reports
Sales data for the monthly Current Market Trends report is compiled from closed sales data reported in the two multiple listing services serving Sullivan County, the Sullivan County MLS and the Greater Hudson Valley MLS. Only single family home sales are included in the compiled data; condominiums, coops, mobile homes and 'seasonal' residences (not winterized for year round use) are excluded. Other news sources often report statistics based on a larger data set of "all residential sales", which does include these other categories.
I made a change in the data methodology as of the March 2011 Current Market Trends Report. Prior to that date, I only pulled sales data from the Sullivan MLS, and did not merge in sales in Sullivan County reported in the neighboring Greater Hudson Valley MLS. The percentage of sales in Sullivan County only reported through the GHVMLS has been growing since early 2010, and the percentage reached a point where it seemed that the GHVMLS data needed to be incorporated in order to provide a more accurate picture. Archived reports prior to March 2011 only include sales data from the Sullivan County MLS, and there may be a discrepency between these reports, and the year-over-year data in reports going forward.
A number of Sullivan County brokers participate in both the Sullivan County and Greater Hudson MLSs, with the result that the same listing is duplicated in both systems. When compiling the "solds" from both systems, I remove the duplicates.
Rather than reporting single month sales data, I use a rolling 3 month average. This is purely a statistical move, to ensure that there is a sufficient sample size. In a single month, there may only 30 or 40 sales, and one or two particularly large sales can wildly skew the average with such a small data set. By using a 3 month rolling average, I'm calculating averages based on 100 to 150 sales, which reduces the impact of any large outlying sales and gives, in my opinion, a far more accurate picture of market trends.