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November 01, 2025, 10:17:58 am

Author Topic: Further Maths SAC - Transformations  (Read 3039 times)  Share 

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Ritzforlife

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Further Maths SAC - Transformations
« on: March 18, 2013, 06:03:53 pm »
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I'm currently doing my further maths SAC. We're required to create a scatterplot with the provided data. My correlation coefficient is a strong positive with r = 0.85

The next question requires us to do a transformation that linearises the data, however my problem is that the scatterplot is already linear and all the transformations all result in a weaker correlation and the coefficient of determination is always only around 60-78%.

Am I missing something? Do transformations always result in the correlation increasing?

Any help is appreciated?

Stick

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Re: Further Maths SAC - Transformations
« Reply #1 on: March 18, 2013, 08:50:04 pm »
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That sounds a bit dodgy to me. Are you sure your data is linear? You might have potentially made a mistake, because it sounds like the data should be non-linear.

To answer your question, no, transformations do not always improve the linearity of data. Think about applying a squared transformation to a straight line, for example. :P
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Lucho23

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Re: Further Maths SAC - Transformations
« Reply #2 on: March 18, 2013, 09:44:00 pm »
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I know from my SAC and what my teacher said, they will most probably ask you to apply a transformation in order to get a stronger relationship. Rarely should you end up with a weaker correlation. Check all your working, you may have made some small error.
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