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for Metrication Month 2020 ( MMe0 ) , Alliance for the Advancement of Technology summarizes metrication of person-height . the centimeter ( cm ) is a practicable unit for a variety of formats for writing height measures . pre-metric measures can also be practicably metricated in terms of a practicable precision , in terms of whole numbers or numbers with a decimal place .
the centimeter ( cm ) is a practicable unit for a variety of formats for writing height measures .
there is a standard for measuring person-height to the nearest 0.1 cm .
measuring in terms of metric units is the most practicable means of metrication .
pre-metric measures can also be practicably metricated in terms of a practicable precision , in terms of whole numbers or numbers with a decimal place .
a pre-metric measure of person-height to the nearest inch can be practicably metricated within 5 cm . if the pre-metric measure was determined to at least the nearest 1/4 inch then the measure can be practicably metricated within 1 cm .
metrication—a process of learning about or practicing the use of metric measures .
a person's height is practicably measured with reference to the metric SI meter ( International System of Units ) . in much of the world it is customary to note person-height to the centimeter . it is also commonly practicable to refer to estimates or approximations of a person's height within 5 cm . a person's height in terms of centimeters can moreover be expressed in terms of a whole number to three places ( using a leading zero for measures less than 1 meter ) .
Australia metricated from the pre-metric foot-inch scales in the 1970s . two Australian standards for noting person-height are measured and self-reported .
person-height (measured), total centimeters NN[N].N
measured per metric scales to the nearest 0.1 centimeter
the standard for measured person-height defines methods for determining height to the nearest 0.1 centimeter.
the centimeter is a practicable unit for different formats for writing height . measuring in terms of metric units is the most practicable means of metrication .
person-height (self-reported), total centimeters NN[N]
person-height is oftentimes self-reported or estimated . if additional methods are not specified , then estimates may or may not count footwear, hatwear , or hairstyle as a part of person-height . at the same time , so many uses of person-height data might not require more than an approximation of person-height . approximate measures can also be useful toward a transition to metrication of person-height data .
person-height data that is self-reported might or might not have been determined to a particular precision , and an uncertainty of measurement might or might not have been established . thus questions about the foot and inch measure might concern whether a particular person-height datum was measured or was estimated . it might also be relevant to know when a person-height datum was measured or estimated . in any case it is important to not rely on an approximation when a precise measurement is called for .
if a measure of person-height includes a fraction of an inch as a part of the noted height , then a rough uncertainty can include the denominator of the fraction . however the denominator won't always equal a rough uncertainty . an expression noted as 1/2 of an inch might not show whether a rough uncertainty was determined from a measure of 8/16 , from 4/8 , from 2/4 , or from 1/2 . that range of scalar-precision represents an 8-fold difference in the precision that might affect whether the measure could be metricated to the centimeter , or would call for an approximation like within 5 cm . at least using a decimal place fraction to significant figures resolves further uncertainties .
an estimated measure can be practicably specified to an approximate person-height within 5 cm . to approximate person-height within 5 cm , take a measured person-height if it is a multiple of 5 cm , or round up to the next higher multiple of 5 cm . the approximate height should be within 5 cm of a measured height ( which is also within 2 pre-metric inches ) . measures from the foot-inch scales within 1 inch are likewise within 2.54 cm , which would not affect an approximation of height within 5 cm .
considering a hypothetical measure of height that is noted in the pre-metric foot-inch scales , 5 foot 0 inch is also equivalent to 60 inches .
the expression indicates a measure with a precision to the inch , or as within 1 inch , and not more precise than within one inch .
thus as an intermediate step an exact conversion of 60 inches is 152.4 cm , for which as another intermediate step it is practicable to round up to 153 cm .
in practice it is often practicable to estimate a person's approximate height within 5 cm , in which it is practicable to round up to the nearest multiple of 5 cm . so the initial 60 inch measure ( 5 foot 0 inch ) could when estimating or approximating within 5 cm be noted as approximately 155 cm .
in each step of this example the scale value rounded is less than the precision of the scale .
thus for a precision of within 1 inch a rounding to the nearest centimeter is not more than 1.27 cm ( rounded up or down as applicable , 2.54 cm divided by 2 ) .
and a precision of within 5 cm is less than 2 inches ( rounding up as applicable ) .
at the same time a pre-metric measure of height within 0.25 inch can be determined to the nearest centimeter .
in the example of a person-height being measured to the nearest 0.1 centimeter , as hypothetically 152.4 cm , then a metric measure might also be written as 1.524 m . although equivalent to 1524 mm , so many references to person-height are not that precise . precision to the millimeter in the pre-metric inch scale would require a precision to 5/127 of a pre-metric inch ( not that a fraction with a large prime number as the denominator would be practicable ) .
for information about unrounded comparisons , not a format !
rounded up to 5 cm increments , reference inches rounded up to nearest inch
acknowledgements to Pat Naughtin and the USMA ( US Metric Association ) mailing list who have previously discussed topics of metrication of person-height .
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