Units and standardisation

Two values, always

Every standardised value keeps both numbers: the value and unit exactly as printed in the paper, and the converted value in the project’s target unit, with the conversion that was applied. Anyone can check the arithmetic, and changing a target unit never loses the reported value.

Conversions that are made

A unit is converted only into another unit of the same kind: force to force, temperature to temperature, concentration to concentration on the same basis.

• Gram-force converts to newtons (1 gf = 0.00980665 N), but only when the paper establishes that the grams are a force and not a mass.
• An unrecognised unit is reported as unrecognised. It is never replaced by the nearest familiar one.

Conversions that are refused

Some conversions need information the unit does not contain. Without it, the value is kept as reported and flagged for a person.

A refusal is not a criticism of the paper. Many good papers report grams per gram without saying grams of what, and the honest response is a flag, not a guess.

• Per cent w/w is not converted to per cent w/v, or the reverse, without a density.
• A wet-basis value is not converted to dry basis without the moisture content.
• A force is not converted to a stress without the probe geometry.

Changing a target unit later

Target units are set in the study configuration and can be changed. Because every row keeps its reported value and unit, the converted values are worked out again from the originals. A value that was flagged as not convertible still waits for a person.