Finding an appropriate class width and constructing class limits
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- Опубликовано: 13 июн 2019
- In this video, we show how to find an appropriate class width for a set of raw data, and we show how to use the width to construct the corresponding class limits. This video is part of the content available for free at www.statsprofessor.com/
Helpful on some test corrections. Big Thanks!!
I love you. Thank you for making this.
U are part of the maths genius God bless you sir
Thank you 😊
It actually helped a lot ☺️
Great!
simple yet very helpful ty
Glad it was helpful!
What's tha difficult part in using online resources for studying? There are too many but only one will fit your style of learning... And for me this ONE is the only video that has lead me to understand what I am seeking for after so many videos this is the only one that fit my logical understanding😂
there it says that the class width should be odd in number, but what if it is even. is it okay?
god bless u
🙏 thank you!
Thanks 😊
Thank you for the great explanation! I have an inquiry regarding the class width. I have noticed that between classes there are small gaps such as the gap between 26.0 and and 26.1. If we had a scenario where we had a data value such 26.05, where would we put it? 26.05 is neither covered by the first or second class by the way.
If you have measurements that have hundredths in them, you should make the limits have hundredths too. For example, 26.00 - 28.99, 29.00 - 31.99, …
Also, you could switch to boundaries, 26 - 29, 29 - 32, 32 - 35, … but with boundaries we follow the left-end-point convention. This means the classes are treated as [26, 29) [29, 32) … so the value 29 is part of the second class not the first because left end points are in the set, not right ones. The class 26 - 29 is really 26 to 28.99999999999…
@@dmcguckian perfect! Thanks a lot!
Hi, this is a great video explaining why using the formula for class width won't always work. Thanks for that! However I would like to ask whether there's a way of finding the correct class width without having to manually work out each single class and then only seeing that 5 won't work at the very end (as in this example). Also, once we know it won't work, how do we find the next minimum class width to use? Here you added 0.1 to each class' width, but how do we work this out instead of having to test, for e.g. 0.1, then if 0.1 doesn't work, 0.2, 0.3 and so on? 😮💨 (P.S. I subbed btw!)
Typically, you would either use software to construct the histogram and distribution or use Excel to speed up the check of your choice for the width. If you could assume the data is symmetric and bell shaped, you could use Sturges’ formula. Beyond that, you would need to use trial and error, but with experience you would be able to guess a workable value in one try.
@@dmcguckian I see, thanks!
I like it vey much !! 😁😁😍😍
Great!
Thanks it helped
Great!
Man I shouldn't even be attending lectures 😅 it took my lecturer 3 days to explain class width
What would the class boundaries will be?
I have videos on this topic, so you can look for the video on boundaries for help, but basically when your limits are whole numbers, the corresponding boundaries are just 0.5 below and above the limits. For example, if your class went from 20 to 29, the boundaries for that class would be 20-0.5=19.5 and 29+0.5=29.5.
W video
YOU CLASS INTERVAL SHOULD BE SIX..6 DUDE
It would be nice if 6 worked, because 5.1 is annoying as a class width. Unfortunately, with 18 classes using 6 leaves the last 2 classes completely empty, which means you're really only putting the data into 16 classes, not 18.
I don't understand class width all to well but my teacher said round up even if you get a whole number so the class width should be 6 yes? Or is my teacher wrong. Genuine question
Usually, going up is the best option. There are times when going up can create to much space which leaves the last class empty. That can happen if you have a large number of classes. Checking your answer is the safest option.
@@dmcguckian Thanks, this helps a lot.
What if 18 students instead of 18 classes?
I’m not sure I understand your question. There are no students in this problem, and there is no general concept of a student in this type of problem. Of course, a specific problem could have students in it, but students aren’t always a part of creating a frequency distribution. The parts of a frequency distribution are: classes and frequencies. Classes have upper limits and lower limits (or upper and lower boundaries). Frequency can be expressed in several ways and is best converted to relative frequency.
The "classes" in the context of statistics has nothing to do with students. Classes ≠ Students
Ager no of classes na pata ho to
Hann
statistics got nothing on me thanks
i think you miss understod how class width work: 5 is the right answer, and you add adding 4 not five. what i mean is this
21-26
26-31
31-36
36-41
41-46
46-51
51-56
56-61
61-66
66-71
71-76
76-81
81-86
86-91
91-96
96-101
101-106
106-111
this is how you do it,
Actually, I think it is you who doesn't understand how class width works. The width is the difference between any two consecutive lower (or upper) class limits (or boundaries). You are using a width of 5 (26-21=5) class boundaries, so you think that your list includes 111. However, your upper limits cannot actually be equal to the upper limit of the next class. If that were allowed, you would not know where to put a value like 26. It is perfectly fine to use a boundary like you have attempted to do, but when using boundaries, we use the left-end-point convention. The left-end-point is inside the interval defining the class, but the right-end-point is not a part of the class. For example, 106 - 111 is actually: [106 - 111). The value 111 is not part of the set, which is a problem since 111 is our largest data value.
Masa u r wrong. Do it again its 21-25, 26-30..... But u have 26 both in the first and second class