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

ManagementGroup(IndicatorStock)MAPEError inReturnExplainedbyForecast(R 2 )RegressionSlope(Return :Forecast)RegressionInterceptMG Sizerelative tototal FraserReturnInterpretationRegression analysis: inferences about reliability, precision, andaccuracy relate to long-term trends (1980-2009).MAPE: expected error in any single year’s forecast.Harrison n/a n/a n/a n/a 1.9% Insufficient data for analysesLateShuswap41% 81%Portage 68% 11%Weaver 45% 14%0.90(significant)0.43(notsignificant)0.56(significant)notsignificant 18.2%significant 0.6%notsignificant5.5% Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Precision: Large amount of inter-annual variation explained byforecasts (R 2 = 0.81) Accuracy: Slope is close to one and intercept is not significantlydifferent from zero, thus long-term accuracy is good. Expected Error: expect forecast to overestimate or underestimatereturn by 41% in any given year. Reliability: Relationship between forecast and return is notstatistically significant, thus returns vary at random relative toforecasts, making forecasts unreliable. Expected Error: expect forecast to overestimate or underestimatereturn by 68% in any given year. Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Precision: Low amount of inter-annual variation explained byforecasts (R 2 = 0.14) Accuracy: Slope departs from one and intercept is not significantlydifferent from zero, thus long-term accuracy is good but largeforecasts tend to underestimate returns. Expected Error: expect forecast to overestimate or underestimatereturn by 45% in any given year.H-6