Important cases where the computational definition of R2 can yield negative values, depending on the definition used, arise where the predictions which are being compared to the corresponding outcomes have not been derived from a model-fitting procedure using those data, and where linear regression is conducted without including an intercept.

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And the measurements came from the photo I took with my iPhone and include with my story, which the anonymous Thingiverse poster then uploaded along with the CAD model he derived from it.

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This is a weighted average of short-term interest rates, corporate-bond yields, share prices and the trade-weighted dollar, with the weights derived from the Fed's model.

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Backtested performance was derived from the retroactive application of a model with the benefit of hindsight.

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Morgan Chase has analysed the Fed's macroeconomic model of the American economy, derived from past behaviour.

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This is demonstrated in the exhibition's giant model of a City Hall Tower for Philadelphia that was never built, a dramatic double helix derived from the discovery of DNA in 1953.

WSJ: Ancient Modernism | 'Louis Kahn: The Power of Architecture' | Vitra Design Museum, Germany | By Colin Amery