Accuracy and Precision Test

[Andrew Nguyen 2K]

Is there a proper quantitative description or value for either accuracy and precision? If so what would be the test for the two? (Is there a test or formula we must use/conduct)

Thank you.

[Devika Nair 2D]

I'm sure there are formulas to determine the precision and accuracy of different values. However, for most chemistry courses, you will not be asked to calculate quantitative values. All you're really expected to know is the definitions of the two. Precision is how close measurements are to each other, accuracy is how close measurements are to the true value. Sometimes, you'll be given a few data points or images and asked to identify different examples as more or less precise/accurate. Most examples will be fairly obvious; you will not need a formula or a test, just your own good judgment.

[Mihir Sukhatme 1D]

A helpful way to remember the application of these definitions is through the dartboard example. If you throw several darts and they are clumped together on the bullseye, you are both precise AND accurate. If they are clumped somewhere else on the board, you are precise but not accurate. A third route is if a few darts land on the bullseye, but others don't. This would be accurate but not precise (not able to be replicated extensively). The final route is if the darts are scattered across the board, then you are neither accurate nor precise.

[Meagan Kimbrell 1I]

As said before, the dart board example is a great way to remember the difference between accuracy an precision. Mr. Lavelle utilized it in his lecture slides, but here is a link that displays the example and has some more information about the topic: https://manoa.hawaii.edu/exploringourfl ... s-accuracy
Figure A represents neither accuracy nor precision
Figure B represents precision
Figure C represents accuracy
Figure represents both accuracy and precision
Hope this helps!!

[Sanjana Sivakumar 2E]

Hello!

As Devika said, at the moment we don't really need to know formulas or anything for precision and accuracy. However, I think that since precision is how close the values are to each other, we could find a quantitative description by finding the range of the values. So we would subtract the highest value by the lowest value to find how much the values differ. And for accuracy, which is how close the observed value is to the true value, we would use the percent error formula:

Percent Error = |Observed value - Actual Value| / Actual Value x 100%

And if you want to go further you could subtract the percent error by 100% to find the percent of accuracy. ( For example if the percent error was 2%, then 100%-2% = 98% accuracy.)

But I don't really think you need to worry about any of this for now. And if anything, I believe we may only look at the percent error for this course.

Hope this helps!

[Sidharth Paparaju 3B]

Accuracy is how close your value is to the actual value, whereas precision is how consistent your data is (each time you measure stuff, are you getting the same value?).

[Emily Quill 2H]

Hi! Yes, accuracy is when your result is close to the actual value and precision is when your answers are close to each other rather than to the correct value. That said you can have both together, neither, or one or the other depending on the scenario.