A method, apparatus and computer program product are provided to determine a measure of probe quality, such as a level of accuracy with which the location of a probe point is defined. In the context of a method and for a plurality of probe points, a distance is determined between a respective probe point and a line representative of a link. For the plurality of probe points, the method also includes determining a difference between a bearing of the respective probe point and a bearing of the link. The method further includes determining the measure of probe quality based upon a product of a representation of the distance between the plurality of probe points and the line representative of the link and a representation of the difference between the bearing of the plurality of probe points and the bearing of the link.