Multiple Linear Regression using "REGRESS"

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Priya 2013-10-5

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评论： dpb 2013-10-15

Hello

I am using regress function for multiple linear regression analysis. Once I obtain the values of coefficients, I substitute in the equtation to get the new / predicted values of y.

Then I make the scatterplot of y_original and y_predicted. How can I show the regression line for equation y = ax1 + bx2 + cx3 + d on this scatter plot ? What code should I write for this problem ?

Secondly, How can I find the random error for this multiple linear regression relationship ?

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Priya 2013-10-13

Thanks , this means I cannot plot a multidimensional plot, which can show me the relationship of all three variables (x1,x2,x3) with y ????

Secondly, every regression equation has some random error associated with it. How can we find that random error and what can we conclude out of it ? How shall we interpret that random error ?

Thanks

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回答（2 个）

dpb 2013-10-5

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s=sprintf('y = %.2f*ax1 + %.2f*x2 + %.2f*x3 + %.2f', b); text(x,y,s)

b is the coefficient matrix from regress; x, y are the coordinates of location where you wish to write the equation in the units of the x- and y-axes used for scatter

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Priya 2013-10-13

Thanks , this means I cannot plot a multidimensional plot, which can show me the relationship of all three variables (x1,x2,x3) with y ????

Secondly, every regression equation has some random error associated with it. How can we find that random error and what can we conclude out of it ? How shall we interpret that random error ?

Thanks

Priya 2013-10-15

@ Image Analyst :

Thanks. Now after applying regress, I get the coefficients a,b,c,d for the following equation:

y_predicted = a.x1 + b.x2 +c.x3 + d

When I substitute these coefficients a,b,c,d along with x1 dataset, x2 dataset, x3 dataset respectively into the equation,I will get the y_predicted dataset. For making a scatter plot between y_original dataset and y_predicted dataset, I use use the following command:

plot(y_predicted,y_original,'o')

Question is:

How can I show the line representing the above equation ( y_predicted = a.x1 + b.x2 +c.x3 + d ) on this scatter plot ?

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Priya 2013-10-13

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/89254-multiple-linear-regression-using-regress#answer_99488

Thanks , this means I cannot plot a multidimensional plot, which can show me the relationship of all three variables (x1,x2,x3) with y ????

Secondly, every regression equation has some random error associated with it. How can we find that random error and what can we conclude out of it ? How shall we interpret that random error ?

Thanks

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Priya 2013-10-15

No, in this case I have only two variables : y_predicted which is obtained by substituting the values in the above regression equation and y_original (input y dataset).

I can plot the scatter plot, but don't know how to show the line on the plot.

Is it possible to show the line represented b this equation on the scatter plot.

dpb 2013-10-15

编辑：dpb 2013-10-15

在 MATLAB Online 中打开

Oh, misinterpreted the question or the intended use of "line" -- that there's no line on the plot by your above command is because that's what you told it to do...

plot(y_predicted,y_original,'o')

says use the 'o' marker; you didn't specify a line style so Matlab obeyed and didn't, either. Use

plot(y_predicted,y_original,'o-')

or alternate linestyle of choice.

doc plot % documents above behavior and marker/linestyle choices

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