(MONEY Magazine) – If you want a good clue about where housing prices are headed in your area, here's one key piece of research that can help you: find out whether the average number of days that houses have remained on the market before selling has been expanding or contracting. To obtain that information, simply ask three or four local brokers. If the number is expanding, you live in an area that conforms to the national trend. According to the Better Homes and Gardens Real Estate Service 1990 Housing Cost Survey, when a house was put on the market in 1989, it remained there, on a national average, 97 days before being sold. In 1990, according to figures in the same survey, it took an average of 105 days to find a buyer. If the pace of sales is slackening in your area, you as a buyer have the advantage of being able to bid low. In a market that's cooling off, today's lowball offer often becomes tomorrow's generous bid. Lowballing is particularly sound strategy if your housing goals are flexible. On the other hand, if you've found your dream house, you risk losing it if you come in with an offer that's too low. If the number of days that houses stay on the market is contracting, your best strategy is to line up financing in advance and be ready to move quickly. In a market that is heating up, today's asking price could very well be tomorrow's bargain.

BOX: HEATING UP -- OR COOLING DOWN?

The average number of days homes stayed on the market before selling in nine cities:

City 1989 1990 Alexandria, Va. 45 120 Atlanta 120 120 Houston 166 105 New York metro area 140 155 Omaha metro area 153 85 Palm Beach, Fla. 65 180 San Francisco metro area 24 125 Seattle 90 45 Trenton, Mich. 10 14

Source: Better Homes and Gardens Real Estate Service Housing Cost Survey