You can have error both human error i.e eye balling a measurement to what looks close. and then you have inherent error the error that is already in the equipment i.e a 2 scales one can give a measurement of x when set to zero and if put it on a second scale you could get a measurement of y when set to zero because of calibration gravity etc things you cant control
In Asia especially in China is consumed as food, also has a medicinal use, feeding animals and weaving baskets
