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Coefficient of variance ?

  1. May 10, 2009 #1
    coefficient of variance ????

    ok i know that coefficient of variance is calculated using the equation
    CV=(standard deviation /mean value)*100...

    here is my problem ..Two TV manufacturing companies have provided the mean values and SD of the life time of their TVs .after calculating for one company i got CV as 18.7% and for other i got 16.9%.so i just want to know can i get a idea of what is the better company by looking@ this CV .if so how r u going approach ur answer ?i want reasons for that!.....waiting for help ..thanks you!

    (im giving mean and SD values here if u want them in ur argument but i think CV is sufficient ......for first mean =1495Hrs SD=280Hrs........for second mean=1875Hrs and SD=310Hrs)
  2. jcsd
  3. May 10, 2009 #2


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    Re: coefficient of variance ????

    Well, company 2's TVs last longer on average: 1875 hours versus 1495 for company 1. So if you buy a TV at random, the expected lifetime from company 2's TV is 380 hours longer.

    The standard deviation (or coefficient of variance) simply indicates that there is enough variation that there is substantial overlap, meaning that if you get unlucky, you can end up with a TV from company 2 that dies sooner than a good one from company 1. But the odds are in company 2's favor.

    Of course, none of this necessarily means that company 2 is "better." They could be GE, for all we know - saddled with toxic assets and requiring taxpayer bailouts! Or their TVs may last a long time but be ugly or have tinny sound. As Churchill said, "a vegetarian may well live for 100 years, but it will feel like 200."
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