How to Counter an Appraisers opinion

[Jeff Scholen]

We had an appraiser come back with a opinion less than the sales contract price....about 1% less than that of the contract price. She used comps that were of neighborhoods of lesser quality and she also place weight heavily on a 3 bedroom vs our 4 bedroom. There are no recent sales of houses within the neighborhood we are selling. 

Anyone have experience with countering the opinion of an appraiser on their choice of comparables?