ZW calculations - Page 1

Can anyone tell me how ZW calculations are affected by progeny hip results?  In other words, if a dog has a ZW of 100 and one of his/her kids rates an NZ how does that affect the parent number? Is it a simple 2 point adjustment regardless of the pedigree or is the pedigree a factor also?  

Thanks in advance.

Judy

the simple answer is yes to the former and no to the latter. overall, progeny impact parents' ZW so much that with about 40 offspring or so the parental ZW is pretty much entirely determined by offspring rating. the (dr. beuing, uni giessen) population formula used is HD = RD + g + u where HD is the numeric rating (normal = 1 , nz = 2, ...), RD stands for the breed average, g stands for the genetic impact, and u for the environmental impact. RD, u, and g are estimated by means of mixed model prediction for g and mixed model estimation for u. the SV data is constantly, well quarterly used to update the models. for a dog-specific estimate, keep in mind statistical models are employed, you get HD_i = RD + g_j + m_j + r_ij where i is the ith dog (out of the SV data pool), j is the month number, 1 - 12, the dog was born; m is the 'effect of month born and ris the residual environmental effect. why month? the statistical analysis, as conducted by dr. beuing, separated environmental effect into a (explained) component based on the month of birth and a residual (unexplained) effect. moreover, the calculation of g_i = (g_sire + g_mother)/2. however, as time goes by and offspring are evaluated, adjustments are made via the HD_i and subsequent population and parent HD calculations. 
fundamentally, there are five impact, or knowledge, stages, comprising the lifecycle of a ZW number: 
    1: expected ZW of offspring of (scored) parents: ZW = (ZW_s +ZW_m)/2. that's not really a ZW per se but a an estimate of an estimate. it's still helpful when compared to the population average. for example, the current average ZW in the SV is 85, working lines are a bit below, show lines are somewhat above (source: L Quoll, 1/24/15). so an expected ZW of a litter above 85 isn't all that promising. 
    2: while the offspring has not been scored, siblings and half-siblings may have been scored and the ZW, still via the offspring's' parents, gets adjusted. this is the last stage, if you will, where the ZW is identical for all litter mates. 
    3: as the population model changes, the ZW for individual litter mates may change in differently, based on changes in the residual environmental components. that's referred to as 'assignment luck' and still independent of the individual contribution, i.e. scored hips, which is the only 'self-contribution' to the dog's ZW.
    4: in addition to the scoring of the hips of, say, the ith sibling, the scoring of its litter mates, n-i, also contributes via the parents ZWs, to the ZW of the ith dog.
    5: as a dog, and its siblings, are bred, the offspring start to contribute, cycling through stages 1-5. as this is taking place, the probabilistic nature of the dogs ZW approaches a somewhat deterministic number revealing the 'true breeding (Z) value (W)' of the individual.
    

as you can see, the direct contribution of a score depends on the lifecycle stage of the ZW as well as the score's deviation from both the population and parent ZWs -- all else remaining equal.