You can see the methodology that went into the report.
…The overall median sales price for Long Island/Queens showed a decline over the prior year quarter. Over the same period, average sales price showed a similar pattern of decline as did the number of sales. Listing inventory continued to expand as did the days on market and listing discount indicators. These market patterns are being seen in many suburban markets across the country, made worse by the turmoil seen in the credit markets since last summer. This has impacted affordability with higher down payment requirements, and more stringent underwriting guidelines applied to buyer mortgage applications. A constraint on the flow of transactions has the effect of reducing the number of sales, which in turn raises inventory levels and tempers the potential for rising prices in the spring market…
Download report: 4Q 2007 Long Island/Queens Market Overview [pdf]