Genetic parameters, including the additive genetic variance (σ2a) and the residual variance (σ2e) were estimated using the REML procedure. Heritability (h2) was defined as the proportion of additive variance over the total variance (σ2p) which is the sum of additive variance and residual variance.
Distribution of breeding value and accuracy
The dogs with low breeding value (low OFA score means a better hip) and with higher accuracy (more related dogs measured, the higher the accuracy) are the most desirable for breeding purposes. The averages over all the dogs are -0.004 and 0.24 for breeding value and accuracy, respectively. Low accuracy means that not many dogs were available to estimate the breeding value.
The range of breeding values in the Labrador Retrievers in this data base is -0.95 (the dog with the best OFA hip score breeding value) to 1.15 (the dog with the worst hip score breeding value). Clearly, many of the dogs recorded in this web site will no longer be available for breeding as the OFA data base has records back 40 years.