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Thread: Help Trying to find Averages With Percentage Ranges (work experience)

  1. #1

    Help Trying to find Averages With Percentage Ranges (work experience)

    Help! I need the average years of experience for individuals who answered a survey with separate ranges.

    If survey respondents answered that...

    24.7% have 1-5 years experience
    10.9% have 6-8 years experience
    18% have 9-12 years experience
    27.6% have 13-18 years experience
    16.7% have 19-25 years experience
    2.1% have 25 years experience

    How do I calculate the total average experience of the group??

    Any help is greatly appreciated!

  2. #2
    Elite Member
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    You must pick a representative age in each classification. The whole range will not do, as you have noticed.

    If you have more data, you can use a Mean, a Median, or a Mode - whatever you think is most representative. Lacking additional information, a midpoint may have to do. The only real problem with this methodology is the last grouping. Are your '25's REALLY all exactly 25? If the group really means "25 or more", then it may be more difficult to find a representative age for that classification.

    Let's see where this leads you.
    "Unique Answers Don't Care How You Find Them." - Many may have said it, but I hear it most from me.

  3. #3
    Elite Member stapel's Avatar
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    Cool

    Quote Originally Posted by ckdowling View Post
    If survey respondents answered that...

    24.7% have 1-5 years experience
    10.9% have 6-8 years experience
    18% have 9-12 years experience
    27.6% have 13-18 years experience
    16.7% have 19-25 years experience
    2.1% have 25 years experience

    How do I calculate the total average experience of the group??
    Assume you have some nice number of people; because of the one decimal place for the percentages, let's go with 1,000 (rather than just 100, which would give us fractional people). Then how many people are in each of the classifications?

    When working with ranges like this, often a midpoint is picked. However, since the last classification isn't a range of values, you may want to specify that you're using the lower endpoint of each classification, unless the directions for this exercise specified something else (and you should have been given specific instructions).

    So the 247 people in the 1-5 classification have a total of 247*1 = 247 years (or, if you use the midpoint, 247*3 = 741 years) of experience. And so forth. How many years do you end up with? Dividing this by the number of people, what then is the average number of years of experience?

  4. #4
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    Here is a graph of the stated percentages
    Capture.PNG
    Notice how it's not an even randomly distributed arrangement? It's not like the height of people in a theater, or the flips of a coin. There's a pattern that looks a bit like a bell curve, but there's also an exception to the pattern. Average would hide the fact that there's a lot of newbies and a small amount of longest termers.

  5. #5
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    Building from post 4, an average of any type reduces numeric data to a single number and therefore LOSES information. The advantage of an average is that it is easier for the human mind to comprehend one number than multiple numbers. The purpose of an average is to indicate what is the typical value.

    In your particular case, you have already summarized the data down to six ranges. The human mind can easily grasp six numbers so the advantage of further reduction is small. Furthermore, in this particular case, what you lose by the reduction is the important fact that you have a bi-modal population, a big group with almost no experience and an even largeer group with substantial experience. If your boss insists on an average, then you can use the advice in posts 2 and 3 to calculate one though I would advise against it.

    If using six ranges is considered more information than the likely users can easily comprehend, I suggest either using quartiles or saying " 25% have fewer than 6 years of experience, 45% have more than 12 years of experience, and 30% are in between." I somewhat prefer reducing to three ranges because it shows clearly that those with experience greatly outnumber those with little experience, and that those with considerable experience represent almost half the entire group. A single number will lose both those pieces of information.

    In general, there are mathematical techniques to summarize data. That is math. How to present data is about psychology.

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