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Biology graph - urgent help needed!

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    Okay this is for my coursework, apparently my line of best fit is 'poor'. Can anyone suggest how I should draw it?

    Graph
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    Aha, OK - I can never remember what the official guidelines for this are from the biology peeps but generally the best bet is to draw a smooth curve through the dots - it doesn't have to touch them all and in fact you usually don't get a perfect curve from your dots, but it should be a smooth curve. I wouldn't join the dots. If you Do join the dots, use a ruler - but it's usually best to draw a line that looks as if it's what your dots would fit to if there weren't any experimental errors. If you get my drift.

    Sorry, explaining this stuff is difficult but I never worked out how to attach pictures - I'll try to do you an example and attach it!
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    (Original post by MadNatSci)
    Aha, OK - I can never remember what the official guidelines for this are from the biology peeps but generally the best bet is to draw a smooth curve through the dots - it doesn't have to touch them all and in fact you usually don't get a perfect curve from your dots, but it should be a smooth curve. I wouldn't join the dots. If you Do join the dots, use a ruler - but it's usually best to draw a line that looks as if it's what your dots would fit to if there weren't any experimental errors. If you get my drift.

    Sorry, explaining this stuff is difficult but I never worked out how to attach pictures - I'll try to do you an example and attach it!
    Yeah, I think I smooth curve is the best way to go. Don't worry if you can't attach a file
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    (Original post by Melanie47)
    Graph
    That's not a line of best fit, you've just joined the points.
    Here's an example - http://www.harcourtschool.com/glossa...s/line_o8.html

    You're probably better off with a curve of best fit.
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    (Original post by Grotbag)
    That's not a line of best fit, you've just joined the points.
    Here's an example - http://www.harcourtschool.com/glossa...s/line_o8.html

    You're probably better off with a curve of best fit.
    Yeah, I know... that's why I was asking for advice. Thanks for the link.
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    Yup, I am in fact completely incapable of uploading the file. They always seem too big and I don't know how to make them smaller :s: (Biologists are allowed to be technophobes, OK?!) But hopefully the link Grotbag (GREAT name) provided is helpful
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    Calculate the centroid and then draw the line
    Centroid=average of all X coordinates and Y .
    That should give you a good line of best fit.
    If it is a curve being plotted, use a "flexi curve " ruler , those bendy ones.
Updated: March 8, 2005
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