Mean Absolute Deviation (MAD) | Math with Mr. J - By Math with Mr. J
Transcript
00:0-1 | Welcome to Math with mr J . In this video | |
00:05 | , I'm going to cover mean absolute deviation . The | |
00:09 | mean absolute deviation gives us the average distance between each | |
00:13 | number in our data set and the mean . So | |
00:16 | how far each number is from our mean , on | |
00:20 | average . And think about it . I mean means | |
00:23 | average absolute means we're going to be working with positive | |
00:28 | distances and then deviation means something differs , it's different | |
00:33 | than the usual . So the average distance that these | |
00:36 | numbers differ from the mean . Now the mean absolute | |
00:40 | deviation gives an idea about how much our data differs | |
00:45 | , so how consistent or inconsistent it is . Does | |
00:49 | the data differ greatly ? Is it all close in | |
00:52 | value or somewhere in between ? This is a measure | |
00:56 | of spread . It tells us how spread out our | |
00:59 | data is . Let's jump into our example and see | |
01:02 | exactly how we do this . The first step that | |
01:05 | we need to do is find the mean . So | |
01:08 | add up all of the numbers and then divide by | |
01:11 | how many numbers we have . So let's calculate the | |
01:14 | mean , three Plus three plus 5 plus eight plus | |
01:23 | eight plus 12 . So we add all of the | |
01:28 | numbers and then divide by how many numbers we have | |
01:32 | and we have six . So three plus three is | |
01:36 | six plus five is 11 plus eight is 19 plus | |
01:42 | eight is 27 plus 12 , gives us 39 And | |
01:48 | we divide by six . So 39 divided by six | |
01:52 | , gives us six and 5/10 or 6.5 . So | |
01:58 | that's our mean . Once we have that we can | |
02:01 | move to the next step . So we need to | |
02:04 | find how far each number is from the mean . | |
02:08 | We do this by finding the absolute value of each | |
02:12 | number minus the mean , we want the absolute value | |
02:16 | . So we get positive distances . Now there are | |
02:19 | different ways to do this step as far as set | |
02:21 | up goes much like most things in math , I've | |
02:24 | seen it set up vertically horizontally , or even in | |
02:28 | tables , whatever works best for you , I'm going | |
02:31 | to calculate this horizontally so side to side . So | |
02:34 | let's take each number , subtract the mean and find | |
02:38 | the absolute value of that . And we'll start with | |
02:41 | three . So the absolute value of three -6 and | |
02:47 | 5/10 plus , I'm going to separate each of these | |
02:52 | with an addition sign because looking ahead , our next | |
02:56 | step , we're going to add these deviations . So | |
03:00 | we have another three -6 and 5/10 And we will | |
03:08 | continue our way through our numbers . So five next | |
03:14 | now I'm running out of room so I'm going to | |
03:16 | go to the next , lying down , so to | |
03:19 | speak , And we have an eight , A couple | |
03:26 | more here , so another eight and then lastly 12 | |
03:39 | , so let's find the absolute value of each of | |
03:42 | these . Starting with three minus six and 5/10 . | |
03:47 | That's going to give us a negative three and 5/10 | |
03:50 | . The absolute value is going to be a positive | |
03:54 | three and 5/10 . So I'm going to make note | |
03:56 | above and below these . So we have two of | |
04:02 | the three minus six and 5/10 . So now we | |
04:06 | have five minus six and 5/10 . That's going to | |
04:10 | give us a negative one in 5/10 . So the | |
04:13 | absolute value is going to be a positive one in | |
04:17 | 5/10 . Eight minus six and 5/10 gives us a | |
04:23 | positive one in 5/10 . So the absolute value is | |
04:26 | a positive one in 5/10 Same for this eight . | |
04:31 | And then the 12 12 minus six and 5/10 gives | |
04:35 | us a positive five and 5/10 . So the absolute | |
04:39 | value is a positive five and 5/10 . So here | |
04:44 | are all of our distances for the numbers within our | |
04:49 | data set . So their distance from the mean , | |
04:53 | Once we have this information we need to find the | |
04:56 | average of those distances . So we add them and | |
05:00 | then divide by the number of numbers we have within | |
05:03 | our data set . So those are steps three and | |
05:06 | four . So let's add and divide . We'll start | |
05:09 | by adding . So we have three and 5/10 plus | |
05:13 | three and 5/10 plus one in 5/10 plus one in | |
05:19 | 5/10 Plus one in 5/10 Plus five and 5/10 . | |
05:27 | So adding those , we're going to get a sum | |
05:30 | of 17 , so that's our total amount of distance | |
05:35 | from the mean , if we add all of our | |
05:38 | distances . So once we have that , let me | |
05:41 | write 17 here . So we got 17 , we | |
05:44 | need to divide by the number of numbers within our | |
05:48 | data set . And that's going to give us our | |
05:50 | mean absolute deviation . So 17 divided by six . | |
05:56 | So 17 divided by six is going to give us | |
05:59 | an answer of 2.83 and that three is going to | |
06:03 | be repeating . So I'm going to round to the | |
06:06 | 100th place , it's going to give us two and | |
06:10 | 83/100 . Again , the answer is going to be | |
06:14 | 2.83 and that three is going to be repeating . | |
06:18 | So I'm rounding to the 100th place . So our | |
06:22 | mean absolute deviation is two and 83/100 . That's the | |
06:28 | average distance for each of our numbers within the data | |
06:31 | set , as far as distance from the mean . | |
06:34 | Again , this is a measure of spread . So | |
06:37 | how spread out are the numbers in our dataset ? | |
06:41 | Now , a very important note here when comparing or | |
06:45 | looking at different mean absolute deviations . The higher the | |
06:49 | mean absolute deviation is , the more spread out your | |
06:52 | data is , The lower the mean absolute deviation is | |
06:56 | , the closer your numbers are together , so there | |
07:00 | you have it . There is how you calculate the | |
07:02 | mean absolute deviation . I hope that helped . Thanks | |
07:06 | so much for watching until next time . Peace . | |
07:11 | Mhm . Yeah . |
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