by Wayne Poholke » Tue 08 Feb 2011 7:37 pm
Hello Gareth
We understand that the Radiographers have been tested in the past and have all scored the same set of X-rays within one point of one another.
Gareth, one or two points are a significant amount when each component of the hip is measured at 0 to 5, and one component 0 to 6. So ONE POINT is a significant difference. Say your dog scores a total of 13 points and the breed average is 12.1, - one point is very significant.
Yes we do know of dogs that in the past have had the same x-ray scored by a second radiographer and they were scored a grade apart.
The different scoring system you refer to is PennHip. The system is being pushed extensively by the University of Pennsylvania particularly in the US and Canada. At this point only 20500 Labrador Retrievers have been scored in these countries, so very little statistical information is available. The world in general is still using the Willis System because it has proven statistically that selection of animals with low scores will result in improvement, generationaly in breeding programs.
PennHip has been available for more than a decade yet so few dogs have been scored under the scheme, in a breed that is one of the most popular in the US, 20500 is very few. That clearly explains that we are not out of whack with the international community. Breeders prefer to use the system they understand and not make a guess at which percentile is within breeding limits with PennHip.
Regards
Wayne