AWWA Articles

TV crime show sparks author’s research on water use data

Robert B. Sowby, water resources engineer at Hansen, Allen & Luce in South Jordan, Utah, specializes in public water systems planning, modeling and energy management. His article, “Conformance of Public Water Use to Benford’s Law,” was published in the December 2018 issue of Journal AWWA.

What was a key finding in your research? I found that water use data follow a curious pattern known as Benford’s law. First observed more than a century ago, Benford’s law predicts the frequency of leading digits in numerical data. In this distinctive pattern, the digit “1” appears more frequently than any other leading digit. We might expect the digits to be evenly distributed one-ninth, or about 11%, of the time, but in data that follow Benford’s law, about 30% of the numbers start with 1 (whether it’s 0.01 or 10,000,000), and the frequency decreases thereafter.

My research demonstrates that certain water use data follow Benford’s law - a novel finding for an old pattern that suggests some practical applications.

How does this research apply to the water industry? Water use data are important for many decisions, such as infrastructure planning and water conservation. But since the data are usually self-reported and lack independent measurements, how do we know they’re accurate? Benford’s law provides a way to validate the data. My research shows how water use data follow this pattern and why deviations may suggest errors, incomplete data or abnormal consumption. For example, the same approach has successfully detected tax fraud, where financial data that didn’t fit the pattern were later found to have been fabricated. In other words, if the data don’t follow Benford’s law, something is wrong. In the water industry, Benford analysis could complement other methods and improve the quality of the data and the resulting decisions we make about managing water.

What sparked the idea for this research? About 10 years ago I saw a TV show, a crime drama, in which the FBI used something called “Benford’s law” to solve the case. That was the first time I heard of it. I didn’t think of it again until earlier this year, when I was advising the Utah Division of Water Resources, looking for ways to improve the accuracy of the data reported by individual water systems. It was then that I began exploring Benford’s law as a method for validating water use data.

How did you address challenges in this research? I’ve never had such extensive technical feedback from so many peer reviewers on a piece of research. To address their comments, I had to acquire some new statistics skills and reformulate my analysis. “Back to the drawing board,” you might say. The project nearly unraveled, but the new approach strengthened it in the end. It was worth doing it right.

What is one of the best books you have read related to the water industry? I recently read Let There Be Water: Israel’s Solution for a Water-Starved World by Seth M. Siegel. It’s the fascinating story of Israel’s successful all-of-the-above approach to total water management. We can all learn something from their experience.

What advice would you give an aspiring author? When it comes to research, make it relevant. In seeking originality and novelty, researchers might inadvertently go beyond the real needs of the stakeholders their research is meant to serve. I know this because I’ve split my career between industry and academia - two different worlds that don’t talk to each other enough. There must be a practical element to your work, something useful and significant for the water profession. I encourage soliciting a variety of opinions to make your work as relevant as possible.

When it comes to writing, learn to be concise. I see a lot of “fluff” - verbal baggage that clutters the author’s message. Some forms of writing require more detail and length, but most can benefit from clearer, simpler language. I recommend the HBR Guide to Better Business Writing by Bryan A. Garner and On Writing Well by William Zinsser. Both are must-reads for aspiring authors.

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