Frequency Tables and Histograms - By Anywhere Math
Transcript
00:0-1 | Welcome to anywhere , Math . I'm Jeff Jacobson . | |
00:01 | And today we're gonna learn how to make a frequency | |
00:04 | table and then from that frequency table how to turn | |
00:07 | it into a history graham . Let's get started . | |
00:28 | Okay , today we're gonna talk about frequency tables and | |
00:30 | hissed A grams . We're gonna start off with frequency | |
00:33 | tables . So a frequency table , it's just a | |
00:36 | table . Uh that organizes your data into intervals and | |
00:40 | intervals that are the same size . So let's look | |
00:43 | at our first example and learn how to make a | |
00:45 | frequency table . Okay , here's example one make a | |
00:48 | frequency table showing the shoe sizes of the students in | |
00:51 | the class . So here is my data for their | |
00:53 | shoe sizes . Uh it's already in order . So | |
00:56 | that's very nice . So let's get started on the | |
00:58 | frequency table . Now freaks . The table is very | |
01:00 | simple . It's just two rows . The top row | |
01:03 | is about your data , whatever your data is about | |
01:05 | . So in our case it's shoe sizes on the | |
01:08 | bottom is always gonna be frequency . Second step it | |
01:12 | to decide what you want to make your intervals . | |
01:15 | You typically want to be around four or five intervals | |
01:20 | unless you have a whole lot of data . And | |
01:22 | then you can you can use you'll probably use more | |
01:25 | intervals than that . Um But if you only break | |
01:28 | it up into two intervals , Well that's not going | |
01:31 | to look very good for your for your instagram . | |
01:34 | So I'm going from four all the way up to | |
01:36 | 10 . So I think I'm gonna go for my | |
01:39 | intervals by two . So I'm gonna go from 4 | |
01:43 | to 6 for my first interview now Your teacher or | |
01:50 | your book might show you something like this . So | |
01:53 | 4-6 Then uh 79 , 10 - 13 . And | |
01:59 | that can work as long as you have integers for | |
02:03 | your data . But if you notice , Well if | |
02:07 | I go from 46 and then 7-9 . Well what | |
02:09 | about a 6.5 ? There's a 6.5 that would have | |
02:13 | no place to go . So instead you would do | |
02:17 | it like this 4-6 . This one would be 6-8 | |
02:21 | . 8 to 10 And 10 to 12 . So | |
02:27 | notice there there are no gaps . So even if | |
02:30 | we have decimals Uh there will be a place for | |
02:34 | him . So now all I need to do is | |
02:37 | find out the frequency of my data values in each | |
02:41 | of these intervals . So I just count . Let's | |
02:43 | see from 46 . How many students had shoe size | |
02:47 | is between four and 6 ? Well here's one 4 | |
02:53 | , 2 , Now here's A six . Now the | |
02:57 | question is do I put this six ? Do I | |
02:59 | count it here or do I count it here ? | |
03:03 | And you have to have a rule because you don't | |
03:06 | want to count them . You don't want to count | |
03:08 | that six twice . So the rule is you include | |
03:12 | the value on the left . So you should probably | |
03:15 | write this down include the left , not the right | |
03:26 | . Yeah . And if you follow that rule you'll | |
03:29 | be fine . So this six , I'm not going | |
03:33 | to include it here . Right . This basically is | |
03:35 | from four all the way up . Right . Up | |
03:38 | to six , not including six . So 1234 There | |
03:42 | were four for students that had a size in that | |
03:48 | interval . Okay , now 66-8 here , I include | |
03:53 | the value on the left . So I'm including that | |
03:55 | six . So here's at six , there's 12 345 | |
04:03 | . I'm not including that eight . So I've got | |
04:05 | five here . Right . You see that now here | |
04:08 | again include the value on the left , not the | |
04:10 | right . So I include the eight in this interview | |
04:12 | . Not to 10 . So there's 1 2 . | |
04:17 | Right ? I don't include the 10 and then this | |
04:19 | 10 is included here . So just one . Okay | |
04:22 | , now always , always , always double check to | |
04:25 | make sure you didn't miss any or or include some | |
04:29 | numbers twice . And we can do that by just | |
04:31 | adding . So that's 9 10 11 12 . Right | |
04:36 | . So I should have 12 values here . 123456789 | |
04:41 | 10 11 12 . And I'm good . Now for | |
04:45 | part B we're gonna learn how to turn this into | |
04:48 | a history Graeme . Ok . Part B . Making | |
04:51 | instagram using the frequency table and it's pretty simple . | |
04:54 | Uh First step draw your axes and label them . | |
04:58 | So I'm gonna start like that and sorry , that's | |
05:03 | not perfect . Um shoe sizes whatever you have on | |
05:07 | top , that's always going to go on your X | |
05:11 | axis , which means my Y axis . That is | |
05:13 | labeled frequency . You got that label now we need | |
05:15 | to figure out well what do I want to be | |
05:17 | counting by ? Uh Well frequency I go from one | |
05:21 | all the way up to five so we can easily | |
05:23 | just count by one shoe size . We use the | |
05:26 | exact same intervals that you have here . Okay so | |
05:29 | there's no you don't have to think about it at | |
05:32 | all . Um So the first one we're starting at | |
05:36 | four , so I'm gonna put a four here and | |
05:38 | that's going to go to six . So I put | |
05:40 | a six there . Okay I don't need to do | |
05:43 | this , I don't need to do 4 to 6 | |
05:46 | . Okay there are no gaps so I'm just gonna | |
05:48 | go 46 Here would be eight . So from here | |
05:53 | to here represents 6-8 uh 10 and finally 12 . | |
06:00 | So I've got all that ready now I'm ready to | |
06:02 | draw my bars and the bars of my hissed a | |
06:06 | gram . The height Is whatever you had for the | |
06:09 | frequency . Right ? So from 4 to 6 that | |
06:13 | interval I had a frequency of four . So from | |
06:18 | here to here all the way up to four draw | |
06:23 | bar the difference with his diagrams and bar graphs . | |
06:27 | It looks very similar to a bar graph , but | |
06:29 | there should be no gaps . Okay so now here | |
06:33 | 6-8 , The frequency was five , so 6-8 , | |
06:37 | It's up to five just like that notice they're touching | |
06:43 | , that's what it should look like for a history | |
06:45 | Graham . 8 to 10 , frequency of 8 to | |
06:48 | 10 had a frequency of two . So that is | |
06:52 | right about there . and finally from 10 to 12 | |
06:57 | the frequency was only one and that's gonna be just | |
07:02 | like that . Okay . Um finally I'll add a | |
07:06 | little uh title at the top . You don't need | |
07:10 | a key for instagram , so I'll just say for | |
07:14 | the title students shoe size , here's one to try | |
07:21 | on your own . Okay , example to instead of | |
07:31 | making it instagram , we're gonna learn how to use | |
07:33 | one to answer three questions . So here is our | |
07:36 | history Graham , it's about the winning speeds at the | |
07:39 | Daytona 500 . So first question A Which interval contains | |
07:45 | the most data values ? So if you look at | |
07:48 | our history graham here , Remember the most amount of | |
07:52 | data values will be the bar that is the highest | |
07:54 | , the tallest . So if you look over here | |
07:57 | , which one is it ? Well , you can | |
07:58 | see that it is the interval of 150-159 mph . | |
08:05 | Most of the winning speeds for the Daytona 500 were | |
08:09 | within that interval . Okay . And part b how | |
08:13 | many of the winning speeds are less than 100 and | |
08:15 | 40 MPH . So if we look , let's see | |
08:19 | for 120 to 100 and 29 MPH in that interval | |
08:25 | there was only one winning speed , It was in | |
08:27 | that it's pretty slow for the Daytona 500 . Uh | |
08:31 | And then let's see from 100 and 30 to 139 | |
08:37 | in that interval , let's see there were 44 winning | |
08:41 | speeds in that interval , and let's see one plus | |
08:45 | four , that would give us for five total Winning | |
08:49 | speeds that were less than 140 mph . And finally | |
08:54 | part see how many of the winning speeds are at | |
08:56 | least 160 mph . So let's look well from At | |
09:01 | least means 160 or greater . Right , so at | |
09:06 | 160 to 169 that interval there were seven , seven | |
09:13 | speeds in that interval . Seven winning speeds in that | |
09:15 | interval . And then from 100 and 70 to 100 | |
09:18 | and 79 MPH , there were five . So we | |
09:24 | have those up , seven and five would give us | |
09:26 | 12 . So there were 12 total speeds that were | |
09:30 | at least 160 mph , that won the Daytona 500 | |
09:35 | . Now , before you get to the , on | |
09:37 | your own , if you notice this history graham , | |
09:39 | you'll notice It's not like the one we did an | |
09:42 | example one . Right , we go from 150 to | |
09:48 | 150 , - 169 . Uh they're not exactly the | |
09:51 | same number . And that's because all our values were | |
09:55 | whole numbers . They were all integers . Okay . | |
09:57 | We didn't have any like 159.5 mph because if we | |
10:02 | did then would we be kind of stuck ? We | |
10:05 | would fall in between those two intervals . So if | |
10:08 | you have all whole numbers then this type of history | |
10:11 | game will work fine . But if not like shoe | |
10:14 | sizes , if you got decimals , you gotta be | |
10:16 | careful and do what we did . An example one | |
10:19 | . Okay , here's one to try on your own | |
10:28 | . Finally , an example three , we're talking about | |
10:30 | the shapes of distributions now . We use this when | |
10:33 | we have doc plots or hissed a grams . We | |
10:36 | can describe the shape that the history grammar dot plot | |
10:40 | makes . Um So I've got four examples . This | |
10:44 | first one . If you notice you have most of | |
10:46 | your data here on the right side and it's kind | |
10:51 | of going down to the left . So we call | |
10:54 | that skewed left . Okay . We would describe the | |
10:59 | shape of this distribution skewed left . It's going down | |
11:02 | to the left down here . We call that detail | |
11:07 | of the distribution . Okay , So when you're thinking | |
11:11 | of it , you look where is most of my | |
11:12 | data ? And where is very few of my data | |
11:16 | . And that's the direction you're going towards . Where | |
11:19 | there's a few uh where there's a little few amount | |
11:23 | of data values . Okay , The next one . | |
11:26 | Well , here you notice it's pretty even right left | |
11:32 | side and the right side very uh similar . We | |
11:36 | call this this is symmetric , It's got symmetry . | |
11:42 | So the name of that distribution symmetric . Okay . | |
11:45 | And this last one , well , if this was | |
11:47 | skewed left , you notice here here , we have | |
11:50 | most of our data on the left side and it's | |
11:52 | going down to the right side , which means it | |
11:56 | is skewed . Right ? Okay . We would call | |
12:00 | that distribution skewed , right ? And finally , well | |
12:03 | , what if you have one word ? Pretty much | |
12:06 | flat ? Um , This we would call it's uniform | |
12:11 | , or you can also just call it flat flat | |
12:14 | distribution . Okay , So those are the shapes of | |
12:17 | distributions . Here's one to try on your own . | |
12:27 | Thanks for watching . And if you like this video | |
12:30 | , please subscribe . |
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