What's the difference between accuracy and precision?

Foto van bijdrager Alicia RaeburnAlicia Raeburn4 mei 20224 min. leestijd
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Summary

Accuracy and precision are both ways to measure results. Accuracy measures how close results are to the true or known value. Precision, on the other hand, measures how close results are to one another. They’re both useful ways to track and report on project results.

Accuracy and precision are often used interchangeably in normal life. But as terms of measurement, they’re defined differently. Just because a measurement is accurate does not mean it’s precise, and vice versa. 

Both accuracy and precision are critical aspects of producing high-level work, but what are they? Let’s take a look at the difference and how—and when—you should use each one.

What is the difference between accuracy and precision?

Accuracy and precision are both forms of measurement that define how close you are to hitting a target or achieving a goal. Accuracy evaluates how close you are to the true value of the measurement, while precision shows how close the measured values are to one another. 

Accuracy vs. precision: the bullseye example

The bullseye example is the most common way to show the difference between accuracy and precision. Think of throwing darts at a bullseye. The goal is to be both accurate and precise. In other words, to hit the bullseye as frequently as possible. If you’re simply accurate, that means you’re throwing darts that are landing close to the bullseye, but you’re not hitting the bullseye every time. If you’re simply precise, that means your darts are landing close to one another, but not necessarily close to the bullseye. But when you’re accurate and precise, your darts will land in the bullseye every time—the best case scenario.

What is accuracy?

Accuracy measures how close the result is to the actual value you were trying to achieve. In other words, it’s how closely you hit what you’re aiming for. Whether that’s a strategic goal or a personal win, high accuracy is when you land directly on your target value. Low accuracy is when you’re way off the mark. You can determine accuracy after a single event, although repeatability will be critical to determining if this can be maintained as a long-term success.

Let’s look at an example. You’ve set a KPI to reduce your site’s bounce rate by 12% in this upcoming fiscal year. If your accurate measurement shows that you hit your accepted value—exactly 12% by the end of your fiscal year—you’ve achieved 100% accuracy in setting and hitting your target KPI.

What is precision?

Precision measures how close your results are to one another. While accuracy can be used in one instance, precision will be measured over time. This is because precision requires repeatability to determine the degree of closeness between each set of measurements. High precision is when your results are similar to each other, while low precision is when they’re all over the map. Measuring precision is helpful in two scenarios:

  1. When you’re trying to avoid making the same mistake

  2. When you’re achieving successful results and want to establish a process for reproducibility

Using the above example, let’s say all your pages' bounce rates were reduced by the same percentage. So every page on your site had a bounce rate move down by the same number, whether that’s 6% or 20%. This is highly precise, even though it’s not accurate.

How do you track and measure accuracy and precision?

To know if you are accurate or precise, you’ll need to track and measure your results. Accuracy and precision are measured differently:

  1. Accuracy measurement: How your result compares to the target value. The closer you are, the more accurate you are. To determine accuracy, you need to have clearly defined goals or success metrics you’re trying to reach.

  2. Precision measurement: How close measurements are to each other. To review for precision, you’ll need to develop a tracking system that shows how multiple results or data points compare to each other over time.

When it comes to a measurement system, you’ll want something that’s easy to manage and accurate. A project management software with universal reporting can help you track—and react to—results in real-time. For example, if you notice consistent results (precise) moving away from your target goal (inaccurate), you may have a systematic error that needs correction.

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Examples of accuracy and precision

Just about everything you read about accuracy and precision will give you the bullseye example used above. But let’s look at some more practical examples of how you would use accuracy and precision in your day-to-day life.

Example 1: Building a shared database

Here’s the scenario: your team has felt scattered recently, so you decide to create a shared database where everyone has access to data and reporting in one, centralized space. You hope that if they’re connected to all information in real-time, it will boost collaboration long-term. 

Here are the four scenarios for how this would go, depending on how accurate and precise your database is:

  1. Accurate: If you’re highly accurate but not as precise, you’ll build the database, but you might only see collaboration increase in one or two projects.

  2. Precise: If you’re only precise, you might add many similar items to the database, but they might not be the ones your team needs to collaborate.

  3. Neither: You try to build a database but you’re the only one who can access it, which doesn’t encourage collaboration.

  4. Both accurate and precise: You build a shared database with a multitude of projects that are easy to collaborate on as a team. The system you use is repeatable, so you can continue to collaborate on new projects as they come up.

Example 2: Improve response rate

Your team sets a goal to respond to customer tickets within 48 hours. 

The scenarios could be:

  1. Accurate: Some tickets are responded to within 48 hours, but some aren't.

  2. Precise: All tickets are responded to in the same amount of time, but not 48 hours.

  3. Accurate and precise: All tickets are responded to within 48 hours.

  4. Neither: No improvement or ticket times get slower.

Example 3: Dressing for work

Let’s look at a simpler, day-to-day example. How do you get dressed for work?

To start, you check the weather report the night before so you can lay out clothes. It’s supposed to rain so you decide to wear waterproof boots and a raincoat, plus bring an umbrella. If it rains, boom—that’s your validation. Your outfit was accurate. If it doesn’t rain, the outfit is still precise—these items are all related to each other—but they’re not accurate. Instead, you’re sweating in your too-heavy clothes and lugging around an unnecessary umbrella.

Which is more important, accuracy or precision?

So which one do you need more of, accuracy or precision? Like many things in project management, the answer is, “it depends.” 

To execute strategic initiatives, you’ll want both. But if you have limited resources or time, you might not be able to guarantee that you’ll have accurate and precise results all the time. In this case, focus on accuracy of a measurement first. But keep in mind that precision is important for follow up. You’ll want to keep experimenting with varying techniques to refine your results, becoming more precise as you test.

Precisely accurate, or accurately precise?

At the end of the day, you’ll need both accuracy and precision to complete your best work. You might develop the skills for precision over time and keep missing your target, until one day it falls into place. Suddenly, your precision is landing you on your target goal over and over again. That’s how you elevate your job, your company, and your work into a much higher level.

To reduce errors and boost productivity, it might be time to get some help. Project management tools track, report, and measure your results for you. We’ll help you streamline your work for more accurate and precise results.

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