The variables X and Y are related by a function f having an unknown vector θ of parameters. Values of Y are measured at known values of X. The measured values are denoted by y and x so that
where ε is a measurement error. In the future it is desired to estimate the value of X (ξ, say) by measuring the value of Y:
This is calibration. The problem is how best to allow for the uncertainty in the elements of θ in the estimation of ξ.
A method of adjusting an instrument so that its reading can be correlated to the actual values that are being measured. Calibration is achieved using methods such as recognized standards or by experimentation. For example, the calibration of flow meters can be achieved by the dilution method in which a concentrated extraneous material is added to the flow stream in the vicinity of the flow meter and its diluted effect analysed further downstream from which the actual flow can be determined. For a material balance, the actual flow can be determined and the flow meter calibration completed. Pressure gauges are calibrated against standards and checked periodically for any drift.
A calibration chart is a graphical representation of values read from an instrument. It is usually presented on the x-axis and the corrected value or quantity on the y-axis. An instrument should be calibrated with a sufficient number of data points to ensure a proper relationship between the measured and indicated value.
The determination of the relationship between the indicated value on a measuring instrument and the true value of the being measured. This may result in the adjustment – or calibration – of the measuring instrument to a set value against a reference input. The true value is the value that would be obtained if all sources of error were eliminated.
‘The process by which the controlling parameters of a model are adjusted to optimize the…degree to which the model’s output resembles the reality that the model is designed to simulate…While validation may actually be impossible in some cases (see Oreskes et al. (1994) Science 263, 641–6), calibration is obviously among the most essential obligation of modelling’ (Clarke in P. Atkinson et al., eds. 2005). Lajoie and Hagen-Zanker (2007) Cybergeo: systs., modél., géostat. 405 create and calibrate a robot land-use model.
Identification of the numerical values of the parameters in an economic model by
(1) using for some parameters the values obtained in other empirical and theoretical studies,
(2) using informed judgement to make the best guess of the values for other parameters,
(3) simulating the model, and
(4) fine-tuning the parameter values by matching the model predictions with empirical observations.
This procedure is most often used in the assessment of business cycle models.
- remanent magnetization
- remanié
- remanié beds
- rematerialization
- remedial maintenance
- Remek, Vladimir (1948– )
- remembering
- re-memory
- remnant arc
- remote
- remote attack
- remote cause
- remote control
- remote-control arm
- frequency reuse
- frequency scaling
- frequency selectivity
- frequency shift keying
- frequency spectrum(of electromagnetic waves)
- frequency standard, primary
- frequency swing
- frequency(symbol: ν or f; unit: hertz)
- frequency synthesizer
- frequency table
- frequency theory of probability