Rounding on Landing Reports Explained and Illustrated

Weights for landing reports and fish ticket may have fractions of pounds, but IFQ reports only allow weights that are whole pounds. However, it is necessary for the totals reported on Fish Tickets to match total IFQ debits.  This page documents the mechanism that eLandings uses to round fractional pounds and maintain matching total weights.

Programmer documentation of rounding explains the software's internal mechanisms. This page explains rounding in customer terms.

A simple example with 1 permit and catch evenly distributed over 4 stat areas

Consider a report with 1 permit and catch of one species distributed over 4 statistical areas. (For eLandings staff, we have a /wiki/spaces/ft/pages/4391021, and the result can be viewed in eLandingsTest when logged in as AMACKEREL.)

In this case the effort was evenly distributed among the four stat areas, so the catch is evenly distributed, with each stat area getting 1.25 pounds. When generating IFQ reports, the pounds are rounded to whole numbers, so each stat area could be expected to get 1 pound, but, that leaves 1 pound uncounted. One stat area must receive an adjustment of +1 pounds to generate the correct total IFQ debit. In this simple example, eLandings must choose which stat area gets the adjustment, and in cases where the choice appears arbitrary, eLandings will make the adjustment to the line with the lowest numbered stat area.

Adjustments can be positive or negative

The initial sum of rounded whole values can be larger than the original total, or smaller.  If the initial sum of rounded whole values exceeds the original total, the correction applied can be negative.  (For eLandings staff, we have a /wiki/spaces/ft/pages/4391273, and the result can be viewed in eLandingsTest when logged in as AMACKEREL.)

In this case the effort was evenly distributed among the four stat areas, so the catch is evenly distributed, with each stat area getting 25,001.75 pounds of catch, and 26.25 pounds of deadloss. When generating IFQ reports, the pounds are rounded to whole numbers, so each stat area gets 25,002 pounds of catch, and 26 pounds of deadloss; but, adjustments are required to generate the correct total IFQ debit. As above, in cases where the choice appears arbitrary, eLandings will make the adjustments to the line with the lowest numbered stat area. Adjustments can be positive or negative, and in this case, the catch adjustment is -1 pound, while the deadloss adjustment is +1 pound.

Adjustments are applied to the largest values when possible

When the distribution of catch is not uniform (that is, some stat areas get a higher percentage of the catch), eLandings attempts to apply any necessary adjustments to the largest catch lines. This is statistically preferable because an small adjustment to a large number introduces less bias than a small adjustment to a small number. (For eLandings staff, we have a /wiki/spaces/ft/pages/4391081, and the result can be viewed in eLandingsTest when logged in as AMACKEREL.)

In this case the effort was unevenly distributed among the four stat areas, so the catch is unevenly distributed. When generating IFQ reports, the pounds are rounded to whole numbers, but those whole numbers don't add up to the total of 1001, so an adjustment is required to generate the correct total IFQ debit. In this case eLandings will make the adjustments to the line with the largest catch value. Adjustments can be positive or negative, and in this case, a catch adjustment of +1 pound is applied to the stat area with the largest catch value.

Multiple IFQ permits

When there are multiple IFQ permits with catch that has an even number (such as 100 lbs), the catch is first allocated by permits (such as 50% - 50%).  For sold weight, the extra 2 pounds goes to the larger permit number (even though the catch is an even number).  For deadloss, the extra 2 pounds goes to the smaller permit number (even though the catch is an even number). Then the catch is split by stat area (75-25).   For the smaller IFQ permit, the sold pound rounds up for the larger stat area and rounds down for the smaller stat area; the deadloss pound rounds up for the smaller stat area and rounds down for the larger stat area.  For the larger IFQ permit, the sold pound rounds up for the smaller stat area and rounds down for the larger stat area.  The a deadloss pound rounds up for the larger stat area and rounds down for the smaller stat area.

When there are multiple IFQ permits with catch that has an odd number (such as 101 lbs),  the weight is first allocated to permits (such as 51% - 50%).  For sold weight, the extra pound goes to the permit with the larger permit number (such as 990052); for deadloss, the extra pound goes to the permit with the smaller permit number (such as 990051).   The catch is then split by stat area percents (such as 75% - 25%).  For the smaller permit (990051), the extra sold pound and an extra deadloss pound is added to the smaller stat area (575731).  For the larger permit (990052), an extra sold pound and an extra deadloss pound is added to the larger stat area (575732).