Sunday, June 20, 2010

Metrics in Stories - AP's Guideline

metric system For U.S. members, use metric terms only in situations where they are universally accepted forms of measurement (16 mm film) or where the metric distance is an important number in itself: He vowed to walk 100 kilometers (62 miles) in a week.

Normally, the equivalent should be in parentheses after the metric figure. A general statement, however, such as A kilometer equals about five-eighths of a mile, would be acceptable to avoid repeated use of parenthetical equivalents in a story that uses kilometers many times.
To avoid the need for long strings of figures, prefixes are added to the metric units to denote fractional elements or large multiples. The prefixes are: pico- (one-trillionth), nano- (one-billionth), micro- (one-millionth), milli- (one-thousandth), centi- (one-hundredth), deci- (one-tenth), deka- (10 units), hecto- (100 units), kilo- (1,000 units), mega- (1 million units), giga- (1 billion units), tera- (1 trillion units). Entries for each prefix show how to convert a unit preceded by the prefix to the basic unit.
In addition, separate entries for gram, meter, liter, Celsius and other frequently used metric units define them and give examples of how to convert them to equivalents in the terminology that has been used in the United States.
Similarly, entries for pound, inch, quart, Fahrenheit, etc., contain examples of how to convert these terms to metric forms.
ABBREVIATIONS: The abbreviation mm for millimeter is acceptable in references to film widths (8 mm film) and weapons (a 105 mm cannon). (Note space between numeral and abbreviation.)
The principal abbreviations, for reference in the event they are used by a source, are: g (gram), kg (kilogram), t (metric ton), m (meter), cm (centimeter), km (kilometer), mm (millimeter), L (liter, capital L to avoid confusion with the figure 1) and mL (milliliter).


Anonymous said...

I would like to see the word "only" stricken from the AP guideline. There are certain cases where the metric value should be required, and the AP guideline, as written, seems designed only to discourage.

The metric value is always important when:
*Referencing a value in the law of a metric country.
*Referencing an athletic performance in which the official records are metric.
*When it is the natural unit system of the source being quoted and that source has, in fact, used metric values.

I have seen numerous examples of the above where only an "english" equivalent is given and the story, frankly, looks stupid because the value doesn't make much sense.

Secondly, I would like to point out that the "abbreviations" are actually symbols defined by the BIPM (Bureau International des Poids et Mesures) in the SI Brochure, or the US equivalent NIST SP 330. The symbols are the same in ALL languages even when the word for a metric unit is different such as Italian quilometro for kilometer. The use of a symbol allows the number and its unit to be understood, even if the surrounding text is in a language not understood, and are therefore preferred to words.

Anonymous said...

Most US publications have an international audience, so they should use metric units.