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The Value of Linear Classification in Boerboels

Improving quality and transparency of data collection and monitoring appraisers

Animals are routinely scored for conformation by specially trained appraisers. It is important that data collected in a consistent and transparent manner. This ensures the quality of data and enhances the public’s understanding of the process.

Practical considerations for the implementation of the classification system

  • One organisation should oversee classifications within the evaluating system.
  • There should be a head-appraiser in charge of training and supervising other appraisers within the evaluating system to achieve and maintain a uniform level of classification.
  • Appraisers must record the trait as observed without adjustment e.g. age, sex or sire.
  • The working information provided to the appraiser should make no reference to the pedigree, owner, or breeder.
  • Appraisers should always rotate classification areas to ensure a good data connection between regions and to minimize the sequential scoring of dogs by the same appraiser. This procedure reduces this risk of appraiser/regional genetics interaction.
  • An advisory group should be installed with expertise in the field of conformation classification, statistics, breeding, and training, in order to monitor and advise on the improvement to the classification system.

Training and monitoring of appraisers

The International Committee for Animal Recording (ICAR) recommends standards for the monitoring and performance evaluation of appraisers. This is an important part of ensuring the standardisation linear classification.


Improve accuracy of data collection within a country, all appraisers should:

  • Apply the same trait definition.
  • Apply the same mean.
  • Apply the same spread of scores.

Tools for objectives:

  • National group training sessions.
  • Statistical monitoring of individual appraisers’ performance with reference to mean, spread and normal distribution of scores.
  • Compute the correlation between the scores of one appraiser and the group. This shows the quality of harmonisation of trait definition between appraisers.
  • Use a group of dogs that is representative of the dog population for training session.
  • Deviations of individual scores are discussed and the correct score for a specific trait on a dog is clarified.

National group training sessions

One way of improving harmonisation of scoring by appraisers is having regular training sessions with a group of appraisers.

There are many ways to accomplish trait harmonisation through training sessions. Normally a training session consists of scoring a group of dogs and the scores of individual appraiser are compared with the scores of the other appraisers.

Attention points are:

Scores of each appraiser are analysed per trait using some analysis tools:

  • Compute the mean and standard deviation of the deviations of the scores on dogs per trait, per appraiser.
  • The deviation is the difference between the score and the average group score for a trait, for a dog. This gives insight in the scoring of individual appraiser: always above or below the mean, more variation in scoring a trait than the group appraiser. (With a test it can be shown if differences found are significant.)
  • Instead of scoring a group of dogs once, the dogs can be scored twice by the appraisers, for example in the morning and in the afternoon. Based on these scores (approximately 20) the repeatability per appraiser per trait can be computed.

National Selection Index (NSI) made up as follows:

  • FTI = Functional / Type Index (Linear classification)
  • FHI = Functional / Health Index (Hips / EB / Prolaps etc.)
  • FTI = Functional / Temperament Index (Test)
  • Estimated Breeding Values (EBV) are also made up with the following:
    • Fertility
    • Motherly Instincts
    • Longevity

To conclude

  • Objective measurement brings about scientific breed improvement.
  • The responsibility for improvement of the breed lies with Board.
  • Improvement will only be achieved if subjective opinion can be put aside and the best, scientifically substantiated, decision can be taken for the breed.