## Accuracy vs Precision [ENDORSED]

Ashlyn_Murray_4C
Posts: 1
Joined: Wed Sep 21, 2016 2:56 pm

### Accuracy vs Precision

Could someone give me a definition of both accuracy and precision, and maybe an example of each? I keep getting them mixed up. Thanks!

Elias Ruben 1O
Posts: 47
Joined: Wed Sep 21, 2016 2:56 pm

### Re: Accuracy vs Precision

Hi, Ashlyn! Accuracy is how close a measured value is to the true value, while precision is how close measurements are to each other. I have an example that really helped me understand the distinction between the two, but it's unrelated to chemistry. If you're playing a game of darts and you hit the bulls-eye, that dart was accurate because it hit the right space on the dartboard. If you repeatedly hit the bulls-eye with several darts, then those darts are both accurate and precise because they hit the right spot AND they were close to each other. If you keep missing the bulls-eye, but your darts are hitting the same area of the dartboard, then they are precise, but not accurate. It is possible to be accurate, but not precise, and vice versa. Now, I'll follow up with a chemistry example. If you want to calculate the molar mass of carbon from an experiment, and you get 12.01 g/mol, that is accurate because the known molar mass of carbon is indeed 12.01 g/mol. If you repeat the experiment and redo the calculation several times with the same answer of 12.01 g/mol, then that is accurate and precise. However, if you performed the calculation multiple times and got 6.00 g/mol each time, it would be precise, but definitely not accurate. Hope this helped!

Khachik_Hmayakyan_2E
Posts: 25
Joined: Sat Jul 09, 2016 3:00 am

### Re: Accuracy vs Precision

Hi Ashlyn, these pictures have always been helpful to me in clarifying the difference between accuracy and precision. It's a simplified way of discerning between the two and realizing why they are important in calculations.
http://www.carolina.com/images/teacher- ... cision.jpg

Rachel Brown 3A
Posts: 52
Joined: Fri Sep 29, 2017 7:06 am

### Re: Accuracy vs Precision

Accuracy is when you continue to hit near the mark or say the center of a target but your collection of shots are a little bit scattered. Precision is when you continue to hit one specific mark over and over again (very close together) but the mark you're hitting is not the center of the target or your actual goal.

Tylor McGrew 1J
Posts: 20
Joined: Fri Sep 29, 2017 7:03 am

### Re: Accuracy vs Precision

In simple terms, having a high accuracy is when you get near the desired point consistently. Having a high precision means you get the same results consistently, but it does not have to be near the desired point.

Richard Braun 1I
Posts: 65
Joined: Fri Sep 29, 2017 7:05 am

### Re: Accuracy vs Precision  [ENDORSED]

Accuracy is how close you are to the actual value, and precision is how close the values are to each other. They can be precise but not accurate.