Sample coefficients of variation?

survival · 2011-04-05 10:45:38

How do I get this? I am on the calculator trying to find which is what.
I have the standard deviations of:
a. 7,11,8,4,2,7,3 Sample standard deviation = 3.16 Need the coefficient of variation??

b. 5,7,9,4,8 Sample standard deviation =2.07 Need the coefficient of variation??

Thanks, I will check back, shortly. I am working on two math classes tonight and one col. pc. (formulas)

bobbym · 2011-04-05 11:06:14

Hi survival;

a)

b)

one col. pc

one col. pc? What is that?

survival · 2011-04-05 11:27:26

It's a computer class that is like math. You have formulas to put in place so the "budget" you're working on or whatever all comes out. Think Excel. If you're off one number the entire spreadsheet/workbook is off.

I am gonna look at the answer you put in. This is all greek to me. Thank you so much!

bobbym · 2011-04-05 11:32:06

Yikes, one wrong answer and it is all wrong?

This is all greek to me.

It is supposed too, there are Greek letters in the formulas.

survival · 2011-04-05 12:17:53

hey, how do you find that on a calculator?

bobbym · 2011-04-05 12:21:00

Hi survival;

Do you have a standard deviation key and a mean key? These are quite common.

survival · 2011-04-05 12:40:05

well, it comes up under Var Stats but does not list the coefficient of variation.
It is also asking which one of those two answers has the higher relative dispersion. I know that co. of var is there somewhere, because the text book said to use the calculator to find it.

bobbym · 2011-04-05 12:50:39

You can divide the standard deviation by the absolute value of the mean. That is probably what they mean.

survival · 2011-04-05 12:56:22

I wish I had found this forum last semester when i had algebra.

bobbym · 2011-04-05 13:00:31

I wish I had found this forum last semester when i had algebra.

Well you should have asked me.

Were you able to get my answers using your calculator?

survival · 2011-04-05 13:13:17

Yes, some of them, but half i did the long way.
This stuff is over my head.

bobbym · 2011-04-05 13:17:50

Hi;

Did you get my same answers of .526 and .313?

survival · 2011-04-05 13:54:08

One more question for the today. Where are Z-scores found on a calculator?
One of my problems is:
The mean for a data set is 71. The standard deviation is 5, and the z-score is 1.04. Find the data value corresponding to the value of z.
What is the raw score?
Sorry for all the questions, i have four more weeks to go.:)

survival · 2011-04-05 13:56:48

Yes, your answers were good. For some reason I had to move the decimal over to the right two places. It is online homework and they will only take it a certain way. The numbers were right, decimal moved.

bobbym · 2011-04-05 14:04:44

That is because in some cases they want the answer as a percentage. So you would multiply my answers by 100 ( that is moving the decimal 2 places to the right )

HelpPppppppp please · 2011-04-13 07:05:16

If I have a coefficient of variation of standard soft drinks market is .2 and the high energy drink market is 2.5 times that. Can I just multiply these and have a new coefficient of variation of .5

bobbym · 2011-04-13 07:41:45

Hi HelpPppppppp please;

Welcome to the forum. When you say the high energy market is 2.5 times that. In what sense? 2.5 times the standard deviation? 2.5 times the mean? 2.5 times what?

Helpppppp please · 2011-04-13 09:04:34

2.5 times the coefficient of variation....the problem gives us the mean and both coefficients of variation, and is asking us to solve for the standard deviation.

Helpppppp please · 2011-04-13 09:07:12

Sorry, it actually only gives us one coefficient of variation of .2 and I would like to assume that. If the other coefficient of variation is 2.5 times that then it will be .5 however I know there is a problem with adding and multiplying standard deviations and you need to convert to variance...therefore I am wondering if this appkys

shadeshahida · 2014-01-07 11:16:13

Hi Bobbym,

Typist Ani can type 40 words per minute with standard deviation of 5 while typist Jura can type 160 words per minute with standard deviation of 10. Which typist is more consistent in her work?

Do i need to divide the 40 words per minutes (40/60) and (160/60) to get the mean. Or is it 40 and 160 are the value of mean?

Thanks!

Bob · 2014-01-07 11:24:29

hi shadeshahida

Standard deviation is a measure of spread so 'more consistent' would be the one with the smaller sd.

Bob

shadeshahida · 2014-01-07 22:30:19

Hi Bob

Means,

Typist Ani:
= 5/40
=0.125

and

Typist Jura:
=10/160
=0.0625

Hence, typist Jura is more consistent in her work, is it?

Please advise. Thanks!

bobbym · 2014-01-07 23:39:03

Hi shadeshahida;

I would stick with the one who had the smallest standard deviation. This is the one that is more consistent and that one is Ani.

Look at it this way, supposing you always need the two of them to perform at their average. Not faster and not slower. Supposing you could tolerate ± 5 from that average. Well, Ani is going to be between 35 and 45 about 68% of the time. Jura, between 155 and 165 only 38% of the time. Ani is more consistent.

Admittedly, this question is not well thought out and the term "consistent" is a little confusing here.

Bob · 2014-01-07 23:47:20

and 40 words a minute is already a mean. It's the average typing rate found by adding up a lot of speeds and dividing by the number of them. That is a mean average.

Bob

Last edited by Bob (2014-01-07 23:58:05)

Math Is Fun Forum

#1 2011-04-05 10:45:38

Sample coefficients of variation?

#2 2011-04-05 11:06:14

Re: Sample coefficients of variation?

#3 2011-04-05 11:27:26

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#4 2011-04-05 11:32:06

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#5 2011-04-05 12:17:53

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#6 2011-04-05 12:21:00

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#7 2011-04-05 12:40:05

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#8 2011-04-05 12:50:39

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#9 2011-04-05 12:56:22

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#10 2011-04-05 13:00:31

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#11 2011-04-05 13:13:17

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#12 2011-04-05 13:17:50

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#13 2011-04-05 13:54:08

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#14 2011-04-05 13:56:48

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#15 2011-04-05 14:04:44

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#16 2011-04-13 07:05:16

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#17 2011-04-13 07:41:45

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#18 2011-04-13 09:04:34

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#19 2011-04-13 09:07:12

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#21 2014-01-07 11:24:29

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