Review

A significant aspect of my job involves defining success, selecting metrics, and measures. I am always on the lookout for anything that can help improve my understanding of how to measure things. Although this book provides a good overview of the history of measurement, I was hoping for a more practical guide to measurement in the modern-era. While there were parts of the history lesson that I enjoyed, the density of insights was not enough to justify the investment for me.

Key Takeaways

The 20% that gave me 80% of the value.

• Measurement provides the mechanism for science, statistics and statecraft
• To measure is to focus on a single attribute
• Three crucial properties that units of measurement must posses:
  • Accessibility → you can’t measure something if you can’t find your measuring standard
  • Proportionality → no one wants to measure mountains with matchsticks
  • Consistency → unexpected variation ruins utility
• To be trusted they need to be traced – to ensure they have not been altered (traceability is important too)
• Elastic units are viewed as primitive – but they seem sophisticated to me. Rich in information, context dependent (shrinking and expanding).
• Replacing units is so disruptive, that often it has to be done alongside other big changes in regime (e.g. the French revolution). Political stability can help unify measures (e.g. The Roman Empire).
• People embrace measurement for it’s utility (in tasks like construction and trade) and to create shared expectations and rules (validation helps with trust)
• Many early forms of measurement were based on body parts. Always available at always at human scale. E.g. feet, cubit (forearm), vepsen (cupped hands), pinch, mouthful
• Bronze Age merchants regulated units without a state by using each meeting as an opportunity to compare and adjust their weights
• The splitting of noun and number was the beginning of written language and data (what the things is + how much there is)

• The metric system was a big moment. The goal to base measures on the impersonal and incorruptible, the earth itself.
  • The meter would be a fraction of the planet’s meridian, an imaginary line running from the North Pole to the South
  • The kilogram would be defined as the weight of 1,000 cubic centimeters of water.
  • They were meant to be the weights and measures for all times and for all people
• The second, the meter and the kilogram are now based on the frequency of cesium, the speed of light and Plank’s Constant.
• Official definitions have changed over time:
  • the history of the meter:
    • 1793 – defined as one ten-millionth of the distance from the North Pole to the equator
    • 1799 – replaced by the meter bar (at the council of the ancients)
    • 1960 – replaced by a number of wavelengths of krypton-86
    • 1983 – replaced by the distance light travels in 1/299792458th of a second
    • 2019 – definition now includes a definition of the second as based on cesium frequency
  • the history of the kilogram
    • 1795 – the mass of one liter of water
    • 1799 – replaced by physical forged platinum object
    • 1889 – replaced by physical forged platinum and iridium, kept under lock and key at BIPM in Paris
    • 2019 – replaced and defined by three fundamental physical constants:
      • Cesium frequency (time/second)
      • ‘Speed of Light’ & ‘Cesium Frequency’ (length)
      • ‘Speed of Light’ & ‘Cesium Frequency’ & ‘Planck’s constant’ (mass/energy)

• The three qualities of the metric system
  1. Interconnection. Capacity unit → constructed of length unit → filled with water gives weight unit
  2. Decimal.
  3. Greek and Latin prefixes to denote multiples and fractions (e.g. Kilo = 1000, cent = 0.01)
• The Kg needed it’s own constant. Planck’s constant: h.
  • The speed of light can’t be exceeded.
  • Planck’s constant can’t be ‘subceeded’. It describes the smallest action possible for elementary particles.
    • Photons occur in discrete units, their energy isn’t infinitely variable, it’s discrete and Planck’s constant defines the distance between those rung
    • Planck’s constant can be measured through using many different methods. One of these methods was used to redefine the kilogram, the Kibble balance.
    • A normal balance weighs one object against another. The Kibble balance weighs an object against an electromagnetic force (with extreme precision). Needs to be operated in a vacuum and you have to factor the Moon’s location.
  • E = mc2, shows that mass can be measured in terms of energy as long as we know the speed of light (universe scale)
  • E = hν, shows that energy can then be measured in terms of frequency, a feature of all electromagnetic waves, as long as we know h, Planck’s constant (quantum scale)
  • You can combine them to m = hf/c2 → defining mass from frequency, Planck’s constant and the speed of light. This equation is how the Kibble balance calculates a kilogram’s weight in terms of electrical forces
  • The Kibble balance is expensive and hard to operate. It’s not easy to recreate the Kg from first principles

• Measurements don’t only benefit from authority, they can create it. Statecraft is about deploying tools of measurement and legibility to better understand and control your citizens. Think land boundaries and taxes.
  • A survey can shrink a huge amount of land – so it can fit in a single mind.
  • The Romans divided Europe into grids, simplifying property rights and taxation
  • England’s Gunter’s chain was used by Cromwell to survey Ireland and Thomas Jefferson to survey the US. The measurement of land is often a prerequisite to conquest.
• Gunter’s Chain. Simple but powerful
  • 66 feet (100 links, the 10th of each was brass)
  • Durable and collapsible
  • Combined base 4 units with with decimal making it easy to measure a..
    • furlong (10 chains)
    • miles (8 furlongs, or 80 chains)
    • acres (1 chain by 1 furlong, or 10×10 chains square)
  • Used for 300 years
  • Two men. One would strike the end into the ground, the other would walk ahead while being directed to keep straight

• Measurement and quantification underpinned the scientific revolution. Better telescopes revealed discrepancies. Myths have been banished

• Statistics unlocked the power of measurement in aggregate
• A fundamental trap of measurement → the more precise you are, the more inconsistent your results often appear to be
• Mayer argued that errors didn’t have to compound, instead they could cancel one another out. The approach was called… ‘the combination of observations’ an early label for statistics. Transmuting error into accuracy.
• Peirce argued in the ‘Illustrations of the Logic of Science’ that the ‘method of science’ is the only secure path to knowledge in the world. All tastes go in and out of fashion. The only thing that produces reliable data, he thought, was experiment and observation. He believed in ‘fallibilism’. There are no facts in life that are beyond doubt. That we can be sure of nothing in science is an ancient truth
• Booth’s work revealed that 33 per cent of the capital’s population lived in poverty. Statistics spurred social reform.
• The discovery of regression and correlation have allowed scientists to draw conclusions from aggregate data that couldn’t have been found otherwise. They amplify the power of relatively shallow measurements, allowing us to find connections between seemingly disparate phenomena.

• Blackboxing is when technical work is made invisible by its own success.
  • Only the input and output of the work remain. Everything else is hidden by the black box.
  • Enhances the authority of science, removes mess so results of research seem definitive and clean
  • It also obscures criticism of the scientific process and hides controversial or arbitrary decisions.