What Is the 80-20 Rule?

The 80-20 rule, also known as the Pareto Principle, is a familiar saying that asserts that 80% of outcomes (or outputs) result from 20% of all causes (or inputs) for any given event.

In business, a goal of the 80-20 rule is to identify inputs that are potentially the most productive and make them the priority. For instance, once managers identify factors that are critical to their company’s success, they should give those factors the most focus.

Although the 80-20 rule is frequently used in business and economics, you can apply the concept to any field. Wealth distribution, personal finance, spending habits, and even infidelity in personal relationships can all be the subject of the 80-20 rule.

How Does the 80-20 Rule Work?

You may think of the 80-20 rule as simple cause and effect: 80% of outcomes (outputs) come from 20% of causes (inputs). The rule is often used to point out that 80% of a company’s revenue is generated by 20% of its customers.

Viewed in this way, it might be advantageous for a company to focus on the 20% of clients that are responsible for 80% of revenues and market specifically to them. By doing so, the company may retain those clients, and acquire new clients with similar characteristics. However, there’s a more fundamental meaning to the 80-20 rule.

Core Principle

At its core, the 80-20 rule is about identifying an entity’s best assets and using them efficiently to create maximum value. For example, a student should try to identify which parts of a textbook will create the most benefit for an upcoming exam and focus on those first. This does not imply, however, that the student should ignore the other parts of the textbook.

Misinterpretations

People may not realize that the 80-20 rule is a precept, not a hard-and-fast mathematical law. Furthermore, it is isn’t necessary that the percentages equal 100%. Inputs and outputs simply represent different units. The percentages of these units don’t have to add up to 100%. It’s the concept behind the rule that matters.

There’s another way in which the 80-20 rule is misinterpreted. Namely, that if 20% of inputs are most important, then the other 80% must not be important. This is a logical fallacy. The 80% can be important, even if the decision is made to prioritize the 20%.

80-20 Rule Background

The 80-20 rule is also known as the Pareto principle and is applied in Pareto analysis. It was first used in macroeconomics to describe the distribution of wealth in Italy in the early 20th century. It was introduced in 1906 by Italian economist Vilfredo Pareto, who is best known for the concepts of Pareto efficiency.

Pareto noticed that 20% of the pea pods in his garden were responsible for 80% of the peas. Pareto expanded this principle to macroeconomics by showing that 80% of the wealth in Italy was owned by 20% of the population.

In the 1940s, Dr. Joseph Juran, a prominent figure in the field of operations management, applied the 80-20 rule to quality control for business production.

He demonstrated that 80% of product defects were caused by 20% of the problems in production methods. By focusing on and reducing the 20% of production problems, a business could increase the overall quality of its products. Juran referred to this phenomenon as “the vital few and the trivial many.”

Benefits of the 80-20 Rule

Although there is little scientific analysis that either proves or disproves the 80-20 rule’s validity, there is much anecdotal evidence that supports the rule as being essentially valid, if not numerically accurate.

Performance results of salespeople in a wide range of businesses have demonstrated success by incorporating the 80-20 rule. In addition, external consultants who use Six Sigma and other management strategies have incorporated the 80-20 principle in their practices with good results.

Example of the 80-20 Rule

A Harvard graduate student, Carla, was working on an assignment for her digital communications class. The project was to create a blog and monitor its success during the course of a semester.

Carla designed, created, and launched the site. Midway through the term, the professor conducted an evaluation of the blogs. Carla’s blog, though it had achieved some visibility, generated the least amount of traffic compared with her classmates’ blogs.

Define the Problem

Carla happened upon an article about the 80-20 rule. It said that you can use this concept in any field. So, Carla began to think about how she might apply the 80-20 rule to her blog project. She thought, “I used a great deal of my time, technical ability, and writing expertise to build this blog. Yet, for all of this expended energy, I am getting very little traffic to the site.”

She now understood that even if a piece of content is spectacular, it is worth virtually nothing if no one reads it. Carla deduced that perhaps her marketing of the blog was a greater problem than the blog itself.

Apply the 80-20 Rule

To apply the 80-20 rule, Carla decided to assign her 80% to all that went into creating the blog, including its content. Her 20% would be represented by a selection of the blog’s visitors.

Using web analytics, Carla focused closely on the blog’s traffic. She asked herself:

• Which sources comprise the top 20% of traffic to my blog?
• Who are the top 20% of my audience that I wish to reach?
• What are the characteristics of this audience as a group?
• Can I afford to invest more money and effort into satisfying my top 20% readers?
• In terms of content, which blog posts constitute the top 20% of my best-performing topics?
• Can I improve upon those topics, and get even more traction from my content than I’m getting now?

Carla analyzed the answers to these questions, and edited her blog accordingly:

1. She adjusted the blog’s design and persona to align with her top 20% target audience (a strategy common in micromarketing).
2. She rewrote some content to meet her target reader’s needs more fully.

Significantly, although her analysis did confirm that the blog’s biggest problem was its marketing, Carla did not ignore its content. She remembered the common fallacy cited in the article—if 20% of inputs are most important, then the other 80% must be unimportant—and did not want to make that mistake. She knew it was necessary to address aspects of the content, as well.

Results

By applying the 80-20 rule to her blog project, Carla came to understand her audience better and therefore targeted her top 20% of readers more purposefully. She reworked the blog’s structure and content based on what she learned, and traffic to her site rose by more than 220%.

What Is the Altman Z-Score?

The Altman Z-score is the output of a credit-strength test that gauges a publicly traded manufacturing company’s likelihood of bankruptcy.

Understanding the Altman Z-Score

The Altman Z-score, a variation of the traditional z-score in statistics, is based on five financial ratios that can be calculated from data found on a company’s annual 10-K report. It uses profitability, leverage, liquidity, solvency, and activity to predict whether a company has a high probability of becoming insolvent.

NYU Stern Finance Professor Edward Altman developed the Altman Z-score formula in 1967, and it was published in 1968. Over the years, Altman has continued to reevaluate his Z-score. From 1969 until 1975, Altman looked at 86 companies in distress, then 110 from 1976 to 1995, and finally 120 from 1996 to 1999, finding that the Z-score had an accuracy of between 82% and 94%.

In 2012, he released an updated version called the Altman Z-score Plus that one can use to evaluate public and private companies, manufacturing and non-manufacturing companies, and U.S. and non-U.S. companies. One can use Altman Z-score Plus to evaluate corporate credit risk. The Altman Z-score has become a reliable measure of calculating credit risk.

How to Calculate the Altman Z-Score

One can calculate the Altman Z-score as follows:

Altman Z-Score = 1.2A + 1.4B + 3.3C + 0.6D + 1.0E

Where:

• A = working capital / total assets
• B = retained earnings / total assets
• C = earnings before interest and tax / total assets
• D = market value of equity / total liabilities
• E = sales / total assets

A score below 1.8 means it’s likely the company is headed for bankruptcy, while companies with scores above 3 are not likely to go bankrupt. Investors can use Altman Z-scores to determine whether they should buy or sell a stock if they’re concerned about the company’s underlying financial strength. Investors may consider purchasing a stock if its Altman Z-Score value is closer to 3 and selling or shorting a stock if the value is closer to 1.8.

In more recent years, however, a Z-Score closer to 0 indicates a company may be in financial trouble. In a lecture given in 2019 titled “50 Years of the Altman Score,” Professor Altman himself noted that recent data has shown that 0—not 1.8—is the figure at which investors should worry about a company’s financial strength. The two-hour lecture is available to view for free on YouTube.

2008 Financial Crisis

In 2007, the credit ratings of specific asset-related securities had been rated higher than they should have been. The Altman Z-score indicated that the companies’ risks were increasing significantly and may have been heading for bankruptcy.

Altman calculated that the median Altman Z-score of companies in 2007 was 1.81. These companies’ credit ratings were equivalent to a B. This indicated that 50% of the firms should have had lower ratings, were highly distressed and had a high probability of becoming bankrupt.

Altman’s calculations led him to believe a crisis would occur and there would be a meltdown in the credit market. He believed the crisis would stem from corporate defaults, but the meltdown, which brought about the 2008 financial crisis, began with mortgage-backed securities (MBS). However, corporations soon defaulted in 2009 at the second-highest rate in history.