? Regarding Calculating ZW #'s - Page 1

Okay, I was just informed that one could calculate their dog's ZW score by taking the mother's score, the father's score, and adding them together, and dividing by two, and then the number left is the ZW score.

Here's my question, what do you do when the mother of your dog has 0/0 hips, and the father has his ZW score, how do you calculate a ZW score for the progeny of said mother and father?

PM if you wish, or email.

Thank you in advance,

Krista

blueskyek9@charter.net

In essence, you cannot as goes the expression apples and oranges. The 0/0 is a hip rating and the ZW is the predictability for the norm that works from the individual dog's hip rating as well of that of all of his scored ancestors, siblings, and progeny.

But, if the bitch with 0/0 hips has a sire and dam who are both S.V.-registered and have "a" stamps, then you can do an approximation for her. Just average the ZW of the sire and dam (you know that already) and divide by 2 and there is her ZW.

But without that scenario, you cannot calculate a meaningful ZW. If I am not mistaken, 0/0 hips are the best rating for that system.

Best Regards,

Bob-O

Hello Bob-O,

thanks, but the mother is 100% Czech, and all the way back to great-grandsires/dams etc...are with the Czech Hip rating system...

Thanks again Bob-O, though I feel I know what your answer will be, seeing as I cannot find a way to calculate the mother's ZW...Thanks anyway!

A newly introduced dog would begin as ZW 100 (represents the average, "a2")

Maybe a fair start for a 0/0 without getting complicated would be a starting score of ZW 95

Or, you could further guesstimate by mapping the known hip ratings of direct ancestors and progeny, and indirectly the siblings and their progeny  (which would affect the rating of the parents of the dog in question).

Ratings are modified from hip rated progeny produced, and the following points are awarded to the producer's final score.  The lower the score the better,
A1 = -5
A2 = +2
A3 = +5  

To translate FCI or Czech ratings, I would guess the following equivalents, and whatever you want to refine inbetween (i.e., 0/1, 1/2)

A = 0/0 = -5

B = 1/1 = +2

C = 2/2 = +5

I see the ZW system as "flawed and pointless", for lengthy reasons, but we are drawn believe in it's mathematics mystique.

I actually thought that once any progeny of a specific sire/dam were also a stamped that would also affect one's ZW.  That it wasn't just a straight up average. 

I think the ZW system is a very good one because it is based on what the dog produces not what he or she is.  The best article I ever read on the ZW system is the one written by Oli on this very site.  He makes it very understandable   Here is the link:

http://www.pedigreedatabase.com/gsd/picturegallery/10.html

Daryl, now that would be a good way to look at it. And, I do agree that the final proof is not guaranteed by the ZW-it is merely another tool that is only useful if ALL ancestors, siblings, and progeny are examined and added to the calculation. And we know that never happens. The ZW is not such a mystique as it is but quantitative analysis. I of course do not know the specific formula!  The solution is only as good as the quantity and quality of the data analysed, but I digress.So, for that reson we must see the ZW as but another tool, and not an axiom for the best breeding practice.

Krista, I would examine the Czech-pedigreed ancestors, and if you see a repetition of passing and good hips, then that is really what you need to see, and that is really what anyone should look at, whether the rating system is F.C.I., O.F.A., B.V.A., or S.V. in origin. I think it is great that someone asks these questions.

Regards,

Bob-O

Wise words, Bob ;-)  I remember a scientific study on the method of quantitative analysis itself, which concluded that comparing QTL analysis in genetic studies, selecting by phenotype has approximately a 20% advantage.

Krista, as Bob stated, best to look for unbroken trends, but also, if less than exemplar hips are to be found in the pedigree, best if they are only on one side (top or bottom).  I'd rather see 5 A2's in three generations on the sire-side, than 1 on the sireside AND 1 on the damside.

Howdy,

Krista, the ZW was intendet to be used as a tool for breeding porposes. I personally feel it is a good attempt, but certainly not more than that. The downfall with the system is simple :

One can only make a correct analysis if he is given ALL info ! Now what has happend in the past ( and sadly enough continues ) is that dogs, that are x-rayed, but where it is clear that the rating will not be good, are simply not submitted for rating. So you have to take this into consideration and look at the ZW with a grain of salt. Annother point is also quite simple, not all of the pups out of a litter will be X-rayed for various reasons. Many go to pet homes, to have these dogs x-rayed is not possible and on top a financial strain on their owners. In a discussion with my Vet, (he is involved in ZW system) he stated :

To get a reliable view of the system, all pups out of a litter need to be x-rayed, the x-ray procedure should be mandetory. Even for dogs that are pets. All x-rays have to be submitted, even if the outcome is not in your favor. If this could be achieved, than this system would work and would be indeed a great tool. If this is done,after only a few years, there could be a dramatic change in the numbers of HD & ED. It then would be possible to determen in which lines there is an increase of HD & ED, and by not breeding with these lines, to avoid HD. HD will possibly never stop entirely, but by making breeding decisions based on facts, there is a good chance to lower the numbers of HD.  But as long as there is only "filtered" data to be used, one can use it as a guideline, not more or less.

Howdy Bob, hope you are fine.

Best Regards Ulli