Correlation Analysis Module Map | |
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Purpose To demonstrate the use of scatterplots and to clarify the meaning of the correlation coefficient computed from them. Summary The module opens with an explanation of the way that paired measurements can be plotted in two-dimensional space. Then positive and negative relationships are demonstrated. Next the correlation coefficient is introduced as a means of adding precision to statements about relationships. To help students gain an intuitive feeling for the meaning of r, they are shown a number of scatterplots and asked to guess the approximate value of the correlation coefficient. Feedback is provided after each guess. Students then are shown a series of scatterplots and are able to alter the values of one or more data points to see the effects on the value of r. The module concludes with some cautions about inferring causality from the presence of correlation. |
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Introduction Scatterplot Examining the scatterplot Positive correlation Negative correlation Uncorrelated variables Correlation coefficient Estimating the relationship Modifying the relationship Causality and predictability Predicting a score |
Summary References |
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Click here to open the worksheet that accompanies this module. (Requires Adobe Acrobat Reader. Click here to get Adobe Acrobat Reader. Internet connection required to download plug-in.) | |