The PBO rounds by applying a set of rules that are simple to implement and apply consistently across all costings.
- Each row of a costing minute’s financial implications is rounded by applying a 3 significant figure rule to determine its level of rounding.
- The largest number in each row (not including the totals) is rounded to three significant figures to determine the level of rounding for the entire row. That is, all figures in a row are rounded to the nearest $0.01 million, $0.1 million, $1 million, $10 million, $100 million or $1,000 million depending on the magnitude of the largest number in the row. As a result, not every number in the row may be rounded to three significant figures.
- Example: A proposal estimated to raise $1,456.789 million (largest estimate) in 2029 30 would be presented as ‘$1,460.0 million’ in the table because the “5” is the third significant figure (i.e. when working through the number from left to right), which would be rounded up to “6” in this example. All other estimates in this row would also be rounded to the nearest $10 million.
- The largest number in each row (not including the totals) is rounded to three significant figures to determine the level of rounding for the entire row. That is, all figures in a row are rounded to the nearest $0.01 million, $0.1 million, $1 million, $10 million, $100 million or $1,000 million depending on the magnitude of the largest number in the row. As a result, not every number in the row may be rounded to three significant figures.
- Table row totals are calculated by summing the rounded numbers in each row.
- Table column totals are calculated by summing the rounded numbers that appear above them.
- Once rounded, all estimates are presented in millions of dollars to the nearest one decimal place (or in rare cases where the estimates are relatively small a row may be presented to the nearest two decimal places).
- Our default rounding convention may be modified on occasion where it fails to clearly present a costing’s financial implications (for instance, where an estimate is particularly uncertain in which case we may present less than three significant digits, or where a proposal specifies an exact amount to be spent, in which case the figures presented would not be rounded at all).