‘parsimony’ should not be included as a principle as relative complexity of an assessment technique should not guide the selection of techniques. the principle of ‘accuracy and reliability’ should not make a distinction between objective and subjective as this did not say anything about the technique’s accuracy. ‘consistency and predictability’ should be added to the principles. The ENA considered that consistency would create a tendency for the same techniques to be applied in the same circumstances, and be applied in a way that results in the assessment technique producing accurate and reliable results over time. Broadly, we are not convinced there is merit in debating which principles should or should not be included in the Guideline. We are not committing to applying only or all of those in the Guideline at the time of review. Having said that, however, we disagree with the ENA's suggestions. We do not agree with the ENA’s view that the principle of ‘validity’ overlaps with the principle of ‘fitness for purpose’. ‘Validity’ relates to extent to which a measure does what it claims to do, whereas ‘fitness for purpose’ acknowledges that a measure used for an informative purpose need not be as precise as a measure used determinatively. We also do not agree with the ENA’s view that ‘parsimony' should be excluded as we consider that assessment methods or forecasting models should be no more complex than required. The description of the principle of parsimony recognises that it becomes relevant where the alternative assessment techniques or forecasting methods measure equally against the other principles. We have decided to retain the reference to objective and subjective techniques in the description of ‘accuracy and reliability’, as we consider that subjective judgement may be less likely to provide unbiased estimates — particularly in contrast to techniques where approach and calculations are set out. However, noting CitiPower, Powercor and SA Power Networks' concern, we have decided to modify the description of ‘accuracy and reliability’ to replace the reference to specific methods to the particular attribute we are concerned about (data-based methods compared to those based on judgement). We have decided not to adopt the ENA’s proposed ‘consistency and reliability’ principle, as we consider that the substance of this principle is covered by the ‘accuracy and reliability' principle.
‘parsimony’ should not be included as a principle as relative complexity of an assessment technique should not guide the selection of techniques. the principle of ‘accuracy and reliability’ should not make a distinction between objective and subjective as this did not say anything about the technique’s accuracy. ‘consistency and predictability’ should be added to the principles. The ENA considered that consistency would create a tendency for the same techniques to be applied in the same circumstances, and be applied in a way that results in the assessment technique producing accurate and reliable results over time. Broadly, we are not convinced there is merit in debating which principles should or should not be included in the Guideline. We are not committing to applying only or all of those in the Guideline at the time of review. Having said that, however, we disagree with the ENA's suggestions. We do not agree with the ENA’s view that the principle of ‘validity’ overlaps with the principle of ‘fitness for purpose’. ‘Validity’ relates to extent to which a measure does what it claims to do, whereas ‘fitness for purpose’ acknowledges that a measure used for an informative purpose need not be as precise as a measure used determinatively. We also do not agree with the ENA’s view that ‘parsimony' should be excluded as we consider that assessment methods or forecasting models should be no more complex than required. The description of the principle of parsimony recognises that it becomes relevant where the alternative assessment techniques or forecasting methods measure equally against the other principles. We have decided to retain the reference to objective and subjective techniques in the description of ‘accuracy and reliability’, as we consider that subjective judgement may be less likely to provide unbiased estimates — particularly in contrast to techniques where approach and calculations are set out. However, noting CitiPower, Powercor and SA Power Networks' concern, we have decided to modify the description of ‘accuracy and reliability’ to replace the reference to specific methods to the particular attribute we are concerned about (data-based methods compared to those based on judgement). We have decided not to adopt the ENA’s proposed ‘consistency and reliability’ principle, as we consider that the substance of this principle is covered by the ‘accuracy and reliability' principle.