Don't eliminate outliers unless you are sure you are fitting the correct model. The left panel shows the data fit with our method to a sigmoid dose response curve. One of the points is declared to be an outlier and removed. The right panel shows the data fit to an alternative model with a biphasic dose-response curve. When fit with this model, none of the points are outliers.
Motulsky and Brown BMC Bioinformatics 2006 7:123 doi:10.1186/1471-2105-7-123