Let's Apply Benford's Law to San Diego City Budgets

Travis Leleu bio photo By Travis Leleu

Benford’s Law is an observation that certain real-world datasets have unbalanced distribution of leading digits. It is applied by forensic accountants and is formally studied by accountants; it has been used to identify possibly forged data in science experiments.

Let’s explore the San Diego City Budgets from 2011-2018 to see if they appear artificial.

FY2011 San Diego Budget
FY2011 San Diego Budget


San Diego City Budgets, 2011-2018


Jupyter Notebook


Individual Year Graphs all pretty much look like the ideal distribution. For example, here’s FY2015:

FY2015 San Diego Budget
FY2015 San Diego Budget

And FY2018:

FY2018 San Diego Budget (Projected)
FY2018 San Diego Budget (Projected)


The San Diego City Budgets all match the expected distribution very closely, for each individual year as well as cumulatively.

FY11-18 San Diego Budget (Projected)
2011-2018 San Diego Budget Data