This is straight from ERA's Start-Up for Real Estate
The open house is another valuable part of the marketing process, offering prospective buyers the chance to view houses in a low-pressure, "browsing" atmosphere. With that in mind, you shouldn't expect it to generate a sale, at least not directly.
What you should look for is interest expressed and requests for private showings made to your sales professional in the days following the open house.
Open houses are always valuable. If many prospective buyers attend, it shows you that the property is attractive and saleable. If very few people show up, it can indicate that the price is too high, and cause you to look for ways to improve curb appeal. Try not to draw your own conclusions - your sales professional will give you a full report on open-house activity and offer a professional assessment of its results.
For more tips visit www.HuntingForYourHome.com
Sales professionals often hold an open house for other sales professionals shortly after a house is listed. This event, usually held mid-week when real estate people can give it their full attention, can be as important to your efforts as your listing in the local MLS. The more professionals who see your house, the more prospects you're likely to reach.