Calculating R-squared | Regression | Probability and Statistics | Khan Academy



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Calculating R-Squared to see how well a regression line fits data

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19 Comments

  1. Here's the question: IS THE ANSWER E?)

    Which of the following tells us how strong the relationship is between two variables?

    a) the slope of a line

    b) the intercept of a line

    c) the coefficient of determination

    d) the coefficient of correlation

    e) both C and D are correct

  2. First year in statistics….do I use parentheses when doing the coefficient of determination? For example, I am confused now because I read that you can't have a negative correlation of determination. For instance, say you had Rxy = -.7….now, would that be like this (-.7)squared, or just -.7 squared…each gives different results….a negative and a positive…but I don't know which one to use? Thanks!

  3. what about when the difference between the "best fit" line is much much larger than the mean and the squared error with the line of "best fit" is actually much larger than the squared error with the mean? then you get a negative r squared?

  4. @norwayte The 12% is unexplained. Real world examples are important here. Suppose x is height of a person and y is weight. Then 88% of the variation in weight can be explained by knowing someone's height. The other 12% is explained by either something else(diet, genetics, etc.), or just randomness (no real cause at all).

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