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Math Help - Engineering stats simple question

  1. #1
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    Engineering stats simple question

    Hi! I know how to construct a stem and leaf plot, but i'm having some issues with a data set. I've always learned to include the gaps because i thought that was one of the main reasons why we use the stem and leaf plot, but this data set is all over the place. Is it ok to leave out the gaps for a data set like this.?.. the current book we're using is quite awful in having examples and or explanations and my precious google has failed me. Any help is appreciated.

    {30, 75, 79, 80, 236, 223, 232, 80, 232, 240, 105, 242, 126, 245, 138, 247, 149, 354, 179, 274, 179, 384, 191, 470}

    I'll have to construct a dot-plot as well, and then a histogram. I guess I am just too used to "nice" data. So any insight on how to organize classes and the such would be helpful as well.
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  2. #2
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    Is that your whole data set?

    If so make the stem in tens and leafs in units.

    i.e 3|0 = 30, 23|3 = 232.

    For a histogram you might want to make your bin size 50 to 500
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  3. #3
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    That is all of the data. Hah. I guess with so many gaps between 30-470 i was afraid of first stem going from 3 to the next stem being 7, then 8, etc.. Just need some reassurance that it's ok to have large jumps like that without showing 40's, 50's, 60's, and whatever else comes up place holders. I would run out of paper. I think since the data is measured I should just take 470-30 and then subdivide the data into 10 equal parts. Maybe 44 for each class size, and then do the frequency/ relative frequencies from there.
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  4. #4
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    Leaving out intervals will not help when showing the spread of the data which a stem and leaf plot is supposed to do.
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  5. #5
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    Agreed. This is why i'm so confused as to why i'd have to make a stem and leaf plot for this data set. There are only 24 values but i'd have to show 28,29,30,31,32,33,34 etc etc which seems awfully tedious and paper consuming just to show the idea which i clearly understand has large gaps nearing the 470 mark. But if this is what i must do then i will. Now i really appreciate nice number sets the book gives us.
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  6. #6
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    Quote Originally Posted by Johanthegnarler View Post
    which seems awfully tedious and paper consuming just to show the idea which i clearly understand has large gaps nearing the 470 mark.
    This is why we use computers ;D
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  7. #7
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    Lol, we have to do the first chapters without. Thanks for your help though. When looking at the data spread there appears to be some negative skewing action going on. I hope that is what I was supposed to gather from this exercise.
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