You may wonder why we spend so much time talking about measurement standards and handling data properly. Two stories....
1. Suppose you are buying fabric, and you and the seller agree to a price over the phone for 10 yards of upholstery fabric. When she makes delivery, you discover that her tape measure went through the washer and dryer and is only 3/4 as long as yours. She insists she is selling you 10 yards (and "proves" it by measuring with her tape measure.)
2. You need ten half inch holes drilled in a piece of aluminum. The shop gives you an acceptable price, so you write up the order for drilling ten holes each 0.500 inches in diameter. The shop owner raises his eyebrows and charges you far more than the original estimate.
It is important that everyone in a transaction agree on units of measurement, and that close attention be paid to the stated accuracy of units!