Averages are just that, averages. Be more concerned that the property is well priced or not. Just because the ratio might be 96%, it doesn't mean you can take off 4% of any asking price.
Instead concentrate on the market value of the particular property. If a house is overpriced you still lose if you use these ratios. If underpriced, someone else will get the house, not you.
Basic negotiating 101. Be able to justify your offer.... more