Sentences with phrase «validation period»
The phrase "validation period" refers to a specific length of time during which something is checked or confirmed to be correct, valid, or acceptable. Full definition
Both the linearity and stationarity assumptions may be checked using the training and validation periods of the instrumental record.
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Two factors appear to be important — their use of the «Lasso» method exclusively to assess this, and the use of short holdout periods (30 years) for both extrapolated and interpolated validation periods.
Prior to its deployment off of New Jersey, the NJORD buoy was deployed off of the coast of Block Island, Rhode Island for an eight - week validation period.
They take on massive risk in the process, and they go through a rigorous validation period to make sure their projects are well - designed, with verification inspections coming after that to make sure they're doing what they said they'd do.
The shaded region envelops the ± 2 standard deviation uncertainty as derived from the validation period.
If you fail to respond within thirty days (known as the validation period) to dispute the debt, it will be assumed to be valid.
The shaded region envelops the ± 2 standard deviation uncertainty as derived from the validation period.
Before the proxy reconstruction is accepted as valid, the relationship between the reconstruction and the instrumental measurements during the validation period is examined to test the accuracy of the reconstruction.
The combination of a high RE and a low CE or r2 means that the reconstruction identified the change in mean levels between the calibration and validation periods reasonably well but failed to track the variations within the validation period.
Because of the autocorrelation in most geophysical time series, a validation period adjacent to the calibration period can not be truly independent; if the autocorrelation is short term, the lack of independence does not seriously bias the validation results.
If the calibration has any predictive value, one would expect it to do better than just the sample average over the validation period and, for this reason, CE is a particularly useful measure.
Stationarity can also be tested for the validation period, although in most cases the use of the proxy relationship will involve extrapolation beyond the range of observed values, such as in the case of point A in the illustration given above.
Besides supplying an unbiased appraisal of the accuracy of the reconstruction, the validation period can also be used to adjust the uncertainty measures for the reconstruction.
well as the mean level in the validation period, in which case CE will be close to zero.
One useful adjustment is to inflate the estimated prediction standard error (but not the reconstruction itself) in the predictions so that they agree with the observed CE or other measures of skill during the validation period.
If the validation period is independent of the calibration period, any skill measures used to assess the quality of the reconstruction will not be biased by the potential overfit during the calibration period.
This calculation will also provide a theoretical MSE for the validation period, which can be compared to the actual mean squared validation error as a check on the method.
Past variations in the climate variable, including those during the validation period, are then reconstructed by using this statistical relationship to predict the variable from the proxy data.
An inherent difficulty in validating a climate reconstruction is that the validation period is limited to the historical instrumental record, so it is not possible to obtain a direct estimate of the reconstruction skill at earlier periods.
The role of a validation period is to provide an independent assessment of the accuracy of the reconstruction method.
Examining the prediction of the reconstruction in a validation period is important, but the length of this period sets limits on a statistical appraisal of the uncertainty in the reconstruction.
For example, the MSE calculated for the validation period provides a useful measure of the accuracy of the reconstruction; the square root of MSE can be used as an estimate of the reconstruction standard error.
where the sum on the right - hand side of the equation is over times of interest (either the calibration or validation period) and N is the number of time points.
Stationarity: The statistical relationship between the proxies and the climate variable is the same throughout the calibration period, validation period, and reconstruction period.
The first step is typically to separate the period of instrumental measurements into two segments: a calibration period and a validation period.
Moreover, a CE statistic close to zero or negative suggests that the reconstruction is no better than the mean, and so its skill for time averages shorter than the validation period will be low.
When the validation period is independent of the calibration period, cross-validation avoids many of the issues of overfitting if models were simply selected on the basis of RE.
If the validation period does not have as strong a trend and the proxies are not skillful at predicting shorter timescale fluctuations in temperature, then the CE can be substantially lower.
This discussion also motivates the choice of a validation period that exhibits the same kind of variability as the calibration period.