R help - Sep 2016 - How to plot the regression line of multivariable linear model?

I'm having a bit of trouble plotting the regression line of 
multivariable linear model.

Specifically my model has one response and two predictors, i.e. it's of 
the form

Y = b_0+b_1*X_1+b_2*X_2

Plotting the regression line for a single predictor model

Y = b_0+b_1*X_1

is simple enough, just call abline() with the coefficients returned by 
lm().

However, I don't know if this can be adapted to multivariable linear 
models.

I also know about curve(), but I don't know how am I supposed to input 
the multivariable model's coefficients into it.

> Specifically my model has one response and two predictors, i.e. it's of
the form
> 
> Y = b_0+b_1*X_1+b_2*X_2
> 
> Plotting the regression line for a single predictor model
> 
> Y = b_0+b_1*X_1
> 
> is simple enough, just call abline() with the coefficients returned by
lm().
Single variable linear model has only 1 regression line.
For two predictors, your regression line! is a surface. (it is not a line
anymore)
For 3 predictors, your regression line! is a volume etc?
> 
> However, I don't know if this can be adapted to multivariable linear
models.
Yes, but in a limited manner. Assume your model is Y ~ x1 + x2 + x3

set x2 and x3 constant  (for instance, to median of the series) predict
(predict.lm) Y.predicted values against x1. Order x1 and  Y.predicted values and
plot them by lines command on Y ~ x1 scatter plot.

Do same thing for other variables.

You might consider the Predict.Plot and TkPredict functions in the
TeachingDemos package.  These help you explore multiple linear
regression models by plotting the "line" relating the response to one
of the predictors at given values of the other predictors.  These
lines can be combined in a single plot (Predict.Plot) or changed
interactively (TkPredict).  See the examples in the help page.

On Sun, Sep 18, 2016 at 9:26 AM, mviljamaa <mviljamaa at kapsi.fi>
wrote:
> I'm having a bit of trouble plotting the regression line of
multivariable
> linear model.
>
> Specifically my model has one response and two predictors, i.e. it's of
the
> form
>
> Y = b_0+b_1*X_1+b_2*X_2
>
> Plotting the regression line for a single predictor model
>
> Y = b_0+b_1*X_1
>
> is simple enough, just call abline() with the coefficients returned by
lm().
>
> However, I don't know if this can be adapted to multivariable linear
models.
>
> I also know about curve(), but I don't know how am I supposed to input
the
> multivariable model's coefficients into it.
>
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-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com