Measurement and data processing

There is a saying in Votic (a language close to extinction found in the Kingiseppsky region of Russia) Kem kḛrtā, mittā, sīz leikkā, and meaning measure thrice, cut once. A similar proverb can be found in a number of different languages, and can be interpreted broadly as meaning ‘give due consideration before you act’. However, in science the literal translation is very appropriate, because how sure can we be of the measurements we are recording? And what can we reliably conclude from our investigation?