OK, admittedly, I don't have any data readily available to back this one up -- but in almost all cases, it seems that a quick 6% price reduction (for example) will work better than two 3% price reductions over time.

For example, the quick six.....

• House is listed for $300K on January 1
• House is reduced to to $280K on March 1 (roughly 6%)

As compared to....

• House is listed for $300K on January 1
• House is reduced to $290K on March 1 (roughly 3%)
  
• House is reduced to $280K on May 1 (roughly 3%)
  

Unless you think you have a great chance of selling the house after just one of the 3% price reductions, it's almost always better to make a faster, larger price reduction.  This price change is more noticeable to buyers and more quickly gets you to a what will hopefully be a realistic selling point.

As a further example, I have seen sellers who have knocked off $5K every other month for an entire year.  Oh, how I wish they had just knocked off $30K that first month.  Each of the progressive $5K reductions had very little impact -- but a quick $30K reduction would have been much more news-worthy and may have inspired a buyer to act.