# back estimation

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## back estimation

A formulaic estimation of a person’s likely blood alcohol concentration at an earlier time X, which may be of interest in a medicolegal context (e.g., drink/drunk driving).
Back estimation formula
Alcohol consumed (g) = (BAC X Widmark factor X Wt) / 100
BAC = Blood alcohol concentration
Wt = Body weight in kg
References in periodicals archive ?
Back calculation was used to estimate body size at settlement for each fish using the equation calculated by ordinary least square linear regression of body size (mm SL) on otolith radius, of the form L = mx + b; where L represents the body length, m represents the slope, x represents the otolith radius at settlement, and b represents the y-intercept.
78 Table 5 Chi-squared values for overall likelihood ratio tests between growth estimates from different combinations of substituted meth ods (observed [Obsv], category adjusted [Adj-cat], formula adjusted [Adj-frm], back-calculation to all annuli [BC-all], and back calculation to the last annulus only [BC-last]) of estimating length-at-age for Scomberomorus commerson and S.
But a back calculation showed it would have been between 220 and 270 at the time of the accident.
By back calculation I figure that two or more 18- to 20-year-old soldiers on every square block of my Syracuse, N.
Other features include multi-point emissivity correction and emissivity back calculation for better accuracy, high-speed auto focusing, automatic/simultaneous temperature scaling, and vertical/horizontal panoramic thermal imaging.
But experts using a back calculation procedure estimated he was over that limit when he crashed.
A scientific back calculation on the amount of drink in Thomas's system determined he would have been driving with 151 milligrams of alcohol in 100 millilitres of blood.
Muldoon, 22, of Mary Street, Blaydon, Gateshead, drove off after the accident but surrendered to police several hours later when he had 29 mcg of alcohol in his bloodstream, below the legal limit, but because the specimen was given some time after the accident, forensic scientists did a back calculation and gave his level as 96mcg of alcohol, almost three times the legal limit, at the time of the accident.
The process of back calculation can be broken down into three steps: verification of the periodicity of annulus formation, establishment of an otolith radius-total body length (OR-TL) relation, and the estimation of size at the time of annulus formation.
The court heard that doing a similar back calculation, the complainant would have had a blood alcohol concentration of a little more than two and a half times the legal driving limit at the time of the alleged attack.
Scientific back calculation gave an estimated reading of around 203 for the time of the accident.
He consumed far more than he admits and back calculation breath test figures showed that at the time of the accident he had a reading of 54 micrograms of alcohol - almost one and a half times over the limit of 35," said Mr Coke.
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