Fraser River Sockeye Fisheries and Fisheries Management - Cohen ...

Table 21 Summary of MAPE and Regression Analyses, testing the relationship between pre-season forecasts and actualreturns for the four run-timing groups and the entire Fraser River forecast. How to interpret statistical outcomes isdescribed in the text above. Proportional size of CU relative to total Fraser return is the average annual value for theperiod 1980-2009. Similar analyses for the 19 indicator stocks are reported in Appendix H.Stock MAPEFraserRiver25% 44%Return Explainedby Forecast (R 2 )RegressionSlope0.84(significant)RegressionIntercept(# fish)notsignificantRun sizerelative tototal Fraser100%Interpretation Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Expect forecast to overestimate orunderestimate return by 25% in any given year. Precision: Moderate amount of inter-annual variation explained byforecasts (R 2 = 0.44). Accuracy: Slope is close to one and intercept is not significantlydifferent from zero, thus long-term accuracy is good.EarlyStuart53% 76%0.99(significant)notsignificant3.3% Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Expect forecast to overestimate orunderestimate return by 53% in any given year. Precision: Moderate/Large amount of inter-annual variationexplained by forecasts (R 2 = 0.76). Accuracy: Slope is close to one and intercept is not significantlydifferent from zero, thus long-term accuracy is good.EarlySummer31% 23%0.60(significant)notsignificant 9.2% Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Expect forecast to overestimate orunderestimate return by 31% in any given year. Precision: Moderate/Small amount of inter-annual variationexplained by forecasts (R 2 = 0.23). Accuracy: Slope is close to one and intercept is not significantlydifferent from zero, thus long-term accuracy is good.78