What’s the point of keeping seven-digit precision?
Note that basing precision on powers of ten is not particularly well-motivated. It arguably makes sense in the sciences where SI is used, but not in general.
Writing 38 instead of 38.81755 saves 6 characters, if nothing else. Keeping unnecessarily many decimals also creates impression of a high precision figure which was misleading here. I am not sure what SI and sciences have to do with that; we use the decimal system for writing numbers, our language is adopted to the decimal system (which is why it may be even preferable to say 40 instead of 38 in the present context—it’s shorter when said aloud) and SI is decimal because of these facts, not the other way around.
Sorry, by using the word ‘precision’ I thought you were invoking the concept of ‘significant figures’, which is used to correctly represent the amount of information in your answer, based on the maximum precision of your instruments. I would argue that in general, binary significant figures are better for that purpose than decimal.
The reason SI is relevant to that, is that the measurements you take tend to be on instruments that are precise to a particular decimal digit. Compare to US units, which are often divided successively in half and thus are much more naturally amenable to binary.
Binary significant figures are better for measuring amount of information, no doubt. But since the numbers are written in the decimal base it is easier to work with decimal significant figures; the ‘instruments’ for measuring life expectancy are statistical surveys which are usually conducted in base 10 (although the units are years, which aren’t particularly SI).
Note that basing precision on powers of ten is not particularly well-motivated. It arguably makes sense in the sciences where SI is used, but not in general.
Writing 38 instead of 38.81755 saves 6 characters, if nothing else. Keeping unnecessarily many decimals also creates impression of a high precision figure which was misleading here. I am not sure what SI and sciences have to do with that; we use the decimal system for writing numbers, our language is adopted to the decimal system (which is why it may be even preferable to say 40 instead of 38 in the present context—it’s shorter when said aloud) and SI is decimal because of these facts, not the other way around.
Sorry, by using the word ‘precision’ I thought you were invoking the concept of ‘significant figures’, which is used to correctly represent the amount of information in your answer, based on the maximum precision of your instruments. I would argue that in general, binary significant figures are better for that purpose than decimal.
The reason SI is relevant to that, is that the measurements you take tend to be on instruments that are precise to a particular decimal digit. Compare to US units, which are often divided successively in half and thus are much more naturally amenable to binary.
Binary significant figures are better for measuring amount of information, no doubt. But since the numbers are written in the decimal base it is easier to work with decimal significant figures; the ‘instruments’ for measuring life expectancy are statistical surveys which are usually conducted in base 10 (although the units are years, which aren’t particularly SI).