We often describe our physical property analysers (PPA) as both accurate and precise. But is there a difference?
Just some of our physical property analysers (PPAs). But can they be described as both accurate and precise?
PPA Accuracy & Precision
Like many a marketer, I am often up to my neck in adjectives. Our products are tall, slender, or beautiful. They can be affordable, inexpensive, or cheap. In some cases, like a certain Belgian lager, they can even be ‘reassuringly expensive’. However, in the world of engineering, other adjectives are more important.
Two such adjectives are ‘accurate‘ and ‘precise‘.
To a lowly marketer like myself, these adjectives have always appeared interchangeable. However, when applied to our physical property analysers, I have been firmly told that they are not the same at all. Here at ATAC, we pride ourselves on manufacturing PPAs that are simultaneously accurate and precise. But these do not mean the same thing. Let me explain.
PPA Accuracy & PPA Precision – The difference
Imagine, if you will, that we have set up a rifle that is fixed into position and fired remotely. In this way we have removed the possibility of human error in taking the shots. The results we will achieve will allow us to make a judgement about how well the rifle itself has been engineered.
Now let’s look at the first two targets above. If we were defining the characterisitics of a rifle, we would have little diffculty describing the first target as demonstrating both accuracy and precision. Likewise, we would have little difficulty describing the second target as demonstrating neither accuracy nor precision. But that doesn’t mean that accuracy and precision are the same thing.
Now let’s have a look at a second pair of targets.
In this first target, the rifle has produced a relatively accurate result. The shots are clustered around the centre of the target, but there is no consistency to the errors. However, in the second target, we can see that the result could not be described as accurate, but at least the errors here appear to be consistent.
In short – the first target demonstrates a high degree of accuracy but a low degree of precision. However, in the second target, we can observe a low degree of accuracy but a high degree of precision.
Accuracy v Precision
Accuracy is how close a measurement or estimate is to the correct value.
Precision is how exact and reproducible a measurement or estimate is.
In the example above, a precise rifle that is not accurate can have its sights adjusted, so that it can become accurate – and its precision will maintain that accuracy over and over again. In terms of our physical property analysers, they need to be both accurate and precise. Our PPAs need to read correct values, and be able to reliably repeat those accurate values time and time again. And that is exactly what they do.
PPA Accuracy & Precision
PPA Accuracy and PPA Precision are therefore not the same thing. As a mere marketer, I have now been educated in the mysterious ways of engineers, and feel the need to spread the word, with an evangelical fervour. These are two adjectives that mean something different and I am now the wiser for knowing.
Of course, the real source of this knowledge was ATAC’s Sales Director (Oil & Gas), John Kelly. When it comes to knowing his way around PPAs, there are few who could claim to be more enlightened. Should I be tempted to evangelise further, then I would recommend that you do two more things:
- Click our link below to our PPA product page. Therein lies wisdom hitherto unknown to man (except for those who already know about process viscometers, vapour pressure analysers, colour monitors, and opacity monitors).
- Or contact John by using our contact page (link below). He will be your oracle in this mysterious world, and he can provide a competitive quote for any of our top quality PPAs. What more could you ask for?
Feature Photo courtesy of Ricardo Arce
