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.return by 47% in any given year.SummerChilko 48% 9.1%0.31(notsignificant)significant23.5% 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 48% in any given year. Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable.Late Stuart 68% 63%0.85(significant)notsignificant7.0% Precision: Moderate/Large amount of inter-annual variationexplained by forecasts (R 2 = 0.63) Accuracy: Slope is departs mildly from one and intercept is notsignificantly different from zero, thus long-term accuracy is good butlarge forecasts may underestimate return. Expected Error: expect forecast to overestimate or underestimatereturn by 68% in any given year.Quesnel 62% 74%0.72(significant)significant 21.6% Reliability: Relationship between forecast and return is statisticallysignificant, thus forecast is reliable. Precision: Moderate/Large amount of inter-annual variationexplained by forecasts (R 2 = 0.74) Accuracy: Slope departs from one and intercept is significantlydifferent from zero, thus long-term accuracy is moderate and thetendency to over-estimate or underestimate returns will vary withH-4