Robin reaction dot com! In this video. I'm going to talk about the differences between
accuracy and precision two different ways that we measure how good our results are and
So just some definitions, that'll do a bunch of examples
accuracy is how close a measured value is to the actual value and
Precision is how close the measured values are to each other. All right, don't think about that too hard
Let's just do the examples and then I'll go back to the definitions
so I'm gonna be doing an example using a dartboard which I think is one of the best and easiest ways to
Understand the two differences between these two concepts. You may have seen it before and sometimes
People just learn what the best analogy is and then you just roll with that. So I definitely think this one is worth learning
so over here in our little gray box, we're going to look at the actual value so we know if we're trying to
Throw something at a dartboard. We're looking to get a bull's eye, right? This is the goal
So now we're gonna say that we have four different darts and in these four tries
we're going to do the best that we can so our first example is going to be
low accuracy and low precision
So for low accuracy, that means that our actual tries are not close at all to the center
So maybe our four darts would end up like this
All right, this was very very
Inaccurate we didn't get anything close to the bull's eye and this is also a very low precision
Guess because remember the precision is how close the measured values are to each other
So not only were these darts not accurate. They also weren't close to each other. They also weren't precise
All right
So now we're going to do our second throw of the dartboard and this is going to be low accuracy but high precision
So it's going to not be accurate
We're not going to get the center of the dartboard
But it's going to be precise the are going to be close to each other
So something that will look like that is maybe a guess like this
So this was super precise all the darts got in the same a got about in the same place
Very very precise all of the values are close to each other, but it's low accuracy, right?
They're not close to what we wanted which was the center of the board
So now next let's do high accuracy low precision
So in this case, we're going to get close to the center, but we're not going very precise. So that would be something like this
All right, so yeah the darts are pretty accurate
You would look at this and say that's pretty good
But they weren't really that close to each other so they weren't very precisely at low precision
And now let's see the best-case scenario of all the show of all these throws which is high
accuracy and high precision
So we're going to get in the middle of the dartboard and they're also going to be really close to each other
So that would be like this
Very accurate very precise
Okay, so that's kind of an analogy. That's easy to understand visually
I think and kind of helps us start to get this concept but in chemistry or science
We're not going to be really throwing dart boards
So let's actually learn something that this that these concepts will be tested towards and in a lot of cases
It's going to be weighing something or getting the mass of something
All right. So now let's say we're going to
weigh a
random cube cube of silver
let's say and let's say that we actually know the exact value of it or your teacher does or somehow we just
Know that this value is exactly
5.00 grams. So now let's go through the four different scenarios that we could get
all right, so first and and for this example
Let's say that it's your job to measure this cube four different times in lab and report your results
So let's say our first example is again low
Accuracy and low precision so we weigh the cube four different times and here is what we get
All right, so we got six point three two grams three point, oh one grams seven point five five grams and four point
Oh two grams. So none of these were that close to five grams, and they also
Weren't close to each other
So they were very low accuracy and they were very low precision if this is what you got when you weighed this cube five times
You should really get your scale fixed or throw it away or check your technique, right?
Something is very wrong if these zero results, so now let's do the next one, which is low accuracy
So it's still not going to close to five grams, but it's high precision
Alright so we got eight point three two grams eight point three five grams eight point two nine grams and eight point three two grams
So in this situation, we are super precise. It's just like the darts
They're all very close to each other, but it's not accurate at all. It's not correct
so in this situation
You probably have something specifically wrong with your scale or your keep on adding something else to it that you don't realize
Right. So in this case the scale may be able to get fixed
Maybe it just adds about three point three grams to anything you weigh, but whatever you want to do
You also wouldn't want to use this scale, right?
And now let's do a high accuracy, but low precision measuring four times
So we're going to be getting close to the actual value, but it's not going to be super precise
The values are going to be a little bit all over the place. So maybe that looks like something like this
So we had five point one five grams four point seven seven grams five point two eight grams and 5.00 grams
So all of these were pretty close to the actual value
But they weren't close to each other
right
The range went all the way from four point seven seven to five point two eight
Not super precise just generally in the ballpark of being accurate
Again, if this is what your scale is giving you
Maybe it's just kind of a really cheap scale like it's kind of knows what's up
But it also gets things like not close to each other so far
I would not want to use any of these three scales and lab I'd throw them all away and then steal a good scale from
Someone who had one. All right
So now let's do the only scale we want to use it's gonna be highly accurate and highly precise
So let's say our four values are something like this
5.01 grams four point nine nine grams 5.00 grams and 5.00 grams
So this is great, right. This is what you want to do
If you measure something four times, you get the same thing almost every time and it should be the actual mass of
What you're measuring and so this is both highly accurate and highly precise
Alright, hope this video helped you understand the difference between accuracy and precision
I would keep on going back to the dartboard and really staring at those guys if they kind of don't make sense to you and
I used I like to think about the dart boards if I ever kind of
I'm having trouble knowing if something is accurate or precise
And happy studying. Hey, I hope you liked that video
Please feel free to like comment or subscribe and if you go to my website
I have a ton of free practice problems. You can check out if you need even more help
You can hire me for one on one private tutoring sessions that are online
Alright, thanks. That's it. Happy studying
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