Example: Correlation coefficient intuition | Mathematics I | High School Math | Khan Academy

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Sal explains the intuition behind correlation coefficients and does a problem where he matches correlation coefficients to scatter plots.
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[@fettishferrubbish8012]

Oh how funny! Yesterday, I was in a physics lab that explored frictional force. And to find the kinetic friction coefficient for a block covered in felt sliding along an aluminum surface, we measured the frictional force of the block by some kind of friction sensor and created a graph where frictional force was the Y and the Normal force acting on the block was the X. With these data points...we created a best fit line...and the slope of that line was the kinetic friction coefficient. Anyways...one of the things we had to check for is what the correlation coefficient was. We managed to get correlation coefficient of .98. which meant that our data points created a line that was straight enough. Our experiment was a success!

[@writerah]

Khan Academy, I absolutely love what you stand for..free education.. Thank you. I have one constructive criticism..if I had a dime for every time you say something like..." We're not going to go into that right now," or " That's beyond the scope of that right now." or " Well, that's a whole other subject that we can't cover now." I'd be a millionaire.

[@unitelanka]

+Rah he's emphasising how subjects are related and have depth. a 10 minute video has to be concise. if you want to check the connected topics check their website.

[@krisswift3564]

Awesome explanation!! My only confusion was that as you were crossing out your "r = 0.02" & "r = -0.72", it looked like you meant to imply that those have a positive correlation. Yes a bit nit-picky but I thought it was worth it to bring it up. Thanks again!

[@inkden1397]

Excellent, thank you

[@omwfg3014]

In the last example the choices should be swapped between B to D. obviously fit matter but calculating r has to do with the ratio of x and y values. As you can see, the ratio depicted by line in graph D is more towards 1 to 1 than the ratio depicted by the line in graph B.

[@mahirbehl5335]

I have a precalc midterm tomorrow. Now i know what residuals are. THANKS

[@xchamaquex3379]

Very help full when needing an example

[@benepokua9421]

This helped me so much thank you

[@BeYourself24x7]

thank you sir

[@MOHSINALI-bk2qo]

thank you

[@IQ88612]

hi, what software or device do you use??

[@khudahafiz478]

sir ...how to find correlation between two values .. I mean the values of r ... can you tell about the formula..plz

[@FROGGKINGG]

Sal sounds like a modded minecraft youtuber lol

[@yrebrac]

my subwoofer tells me there is no low cut on this video :) still, great video

[@deepapreetheesh4303]

If correlation between x and y is r then correlation between x^2 and y^2 is ???

[@Dannyyyyyy]

I believe the scatterplot B is 0.65 and scatterplot D is 0.84. R is the average slope right?

[@dodoblasters]

R is the the correlation coefficient that indicates the extent to which the pairs of numbers for these two variables lie on a straight line. Ranging from -1 to 1. A correlation of -1 indicates perfect negative correlation. Meaning when one variable goes down, the other goes up. A correlation of 1 indicates perfect positive correlation, where both variables go up when either go up. The change in variables (e.g. for every 1 x, you increase y by 3), and therefor the change in slope of the line has nothing to do with calculating R. But where the points lie once the line of best fit is placed are important. If all your points are on the line, R is either -1 or 1 depending on direction. The further your points are from the line of best fit the worse your R value is and closer to 0 (no correlation). When examining B we can see the line is a better fit to our data than the line in D, and we can see a positive correlation. Therefor B must have an R value closer to 1 than D.

[@ghostshade918]

E

[@jaeyounglee5410]

Im in algebra 1 and I learned this... and im in 7th grade...

[@jacobm7026]

yep i took that in 7th grade too. But that doesn't mean they dont offer it in highschool buddy

[@akairov]

hello! I think in Graph B r=0,65 and in Graph D r=1

[@leah9389]

No!

[@nikhilg.2926]

Hello! You are wrong!