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The Science of Accuracy vs. Precision

Some companies focus on either accuracy or precision, but not usually both. But what is the difference and why does it matter?

Well there are 4 stages here…

-       Neither Precise nor Accurate

-       Precise, but not Accurate

-       Accurate, but not Precise

-       Both Accurate and Precise


Neither Precise nor Accurate

In the beautiful image above, the paintbrushes are scattered randomly on the table rather than having been placed precisely and accurately placed into the glass of rinsing water patiently waiting on the table.

Essentially, any instance of random outcomes would be both, neither precise nor accurate. Depending on the objective of the operation, this is usually not good.


Precise, but not Accurate

In the image below, a consistent 19.5 is held, but the objective was to maintain a consistent 20.

In this event, there is a consistent and repeatable demonstration of precision. But because the result is off by .5, it cannot be considered accurate.


Accurate, but not Precise

While accuracy without precision does not always equate to a wrong answer, it can be seen still negatively impact results.

In the image above, the goal is for the blue line to maintain 20. The blue line is seen oscillating around 20. Overall, this will in fact, average to 20 but because the blue line is oscillating and never has actually maintained 20 it is not precise.


Both Accurate and Precise

Getting both accurate and precise results can be difficult. It takes knowledge and experience in a field to do it, but when it is done and demonstrated as repeatable, it leaves behind impressive results.

Accurate and precise can be compared to hitting the bulls eye in a game of darts over and over again without ever missing.

Every operation is different and has different needs to achieve their goals. At Praecis, we strive to give our customers the precision necessary for them to achieve their desired level of accuracy. It is our duty to make sure our customers have consistent, repeatable results, time and time again.

In the image above, the blue line (Critical Point Temperature) uses a precision scale on the right and the orange line (Room Temperature) uses a less precise scale on the left. The two lines are superimposed over each other for reference purposes.

The average maintained on the blue line is 20.000. In this 24-hour test, it can be seen that the fluctuations rarely exceeds ±0.007 (7 millidegrees).

Learn more about Praecis Products.

Learn how Praecis ultra-precision temperature control technology works. 

Whoops! How Much Can We Mess Up?

As we all know from our cracked cellphone screens, technology isn’t perfect. It takes a lot of work for any company to get a product to you in one piece. This is especially true for technology companies whereas the parts and pieces to one product can be in the hundreds or thousands.


But unlike this sphere, nothing is perfect.


In fact, every company makes mistakes. It is often known as ‘dead-on-arrival’ or DOA. Quite frankly, it cannot be completely prevented.  Companies must plan and decide on how much error is accepted and what can it handle. Many larger companies use six sigma as a tool for controlling production errors. In fact the target is less than 0.00034%. This sounds extreme at first but it is important to keep in mind errors can destroy a company’s operation. It also keeps the product from getting to the hands of the customer.

When it comes to manufacturing, engineers utilize an error budget. An error budget is a tool to assist in design. In most operations it is used to predict part accuracy. 

In six sigma the end result depends on the companies operation and the complexity of the product. If there are too many errors, the company may need to shift to a new manufacturing process. While in error budgeting engineers must decide on which errors they can quantify and correct.

In the end, either way, nothing is perfect. But we can get very close.

Precision Engineering is Everywhere

Technology; it’s omnipresent. We use complex tools daily, but inherently forget how much time, energy, and design goes into each new high-technology product, which changes the way we live.

There are many people, and stories, behind every part of your phone, laptop, or car. Engineers, visionaries, programmers, artists, technicians, metal workers, and more spend countless hours designing, optimizing, and building each part, subsystem, and product.

We never think about certain parts, such as a cellphone camera lens, as a challenge to create.

In reality, however, it took a person to design the lens size, another person to replicate this design in CAD software, an ultra-precision engineer to mill the mold for the lens, and ultra-precision temperature control system to get a precise cut to the angstrom level for all eight million reincarnations of the lens.

This lens is but one small part of the cell phone.