Reports this week put home sales in California down 16% in the south and 20% in the north. On Friday, the California Association of Realtors reported that sales were up 3.8% statewide.

How is this possible?

According to Lotus Lou, a spokesperson for C.A.R., it is all about seasonal adjustment and from where the data comes.

The earlier reports were from San Deigo-based DataQuick, a real-estate information firm that gets its data from public records. Its data includes new homes and also is not seasonally adjusted."We track everything that is recorded at the county recorder's office in the way of new and resale houses and condos," said Andrew LePage, a spokesman for DataQuck. "What we offer is just a pure number. I often get quesitons from people scratching their heads over who's data is right."

C.A.R. gets its data from Realtors through multiple listings services and reports a seasonally adjusted annual rate. The C.A.R. data is thus comparable to the national existing and new-home sales data put out by the National Association of Realtors and the Commerce Department, respectively. Earlier in week, DataQuick reported northern California home sales were down 20% and southern California sales were down 16%.

C.A.R. on Friday said statewide home sales rose 3.8% in September to a seasonally adjusted annualized rate of 466,580, up from August's revised pace of 449,290, citing data collected by C.A.R. from more than 90 local REALTOR(R) associations statewide. It said the September pace was down 12.2% from the revised 531,180 sales pace recorded in September 2009.

C.A.R. also said the median price of an existing, single-family detached home sold in September was $309,900, down 2.7% from $318,660 in August, but up 4.5% from $296,610 in September of 2009. That was the 11th consecutive month of year-over-year gains, the Realtors said.

"The inventory of homes priced under $500,000 continues to be lean, which is driving moderate or significant price appreciation in this price category,"said C.A.R. vp and chief economist Leslie Appleton-Young. "Conversely, the inventory of homes priced $1 million and higher is more than double the inventory of the under-$500,000 range, which is contributing to weaker prices at the high end." A video report from Appleton-Young can be found here.

Months supply held steady at 6.2 months, up slightly from August but well ahead of the 4.5-month supply recorded in September of last year. The median number of days on the market also increased to 52.5 from 33.5 at the same time last year.

The national home sales numbers for September from NAR are scheduled for release Monday morning.

Learn more about markets featured in this article: Los Angeles, CA.