Data visualization with SAS programming

Is it possible to show a regression line for specific data points?

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Occasional Contributor
Posts: 7

Is it possible to show a regression line for specific data points?

I have 10 data points representative of years (2003-2012).  I would like to show the regression line for the first 8 points (2003-2010) and have the last two points stand alone.  Is it possible to accomplish this with GPlot?

SAS Super FREQ
Posts: 1,227

Re: Is it possible to show a regression line for specific data points?

Posted in reply to KageKitsune28

Easily done with SGPLOT.  Move the last two points to new columns  (x2, y2) and make them missing in the original columns (x, y).  Now plot a regressioin plot using original columns (x, y).  Overlay a scatter plot with new columns (x2, y2).

Occasional Contributor
Posts: 7

Re: Is it possible to show a regression line for specific data points?

Posted in reply to Sanjay_SAS

Great!  I am going to try that. Smiley Happy Thank you!

Occasional Contributor
Posts: 7

Re: Is it possible to show a regression line for specific data points?

Posted in reply to Sanjay_SAS

Well this was working great until I added the regression line.  The regression line is stretching across all 10 points instead of stopping at 8.

SAS Employee
Posts: 990

Re: Is it possible to show a regression line for specific data points?

Posted in reply to KageKitsune28

Are you using gplot, or sgplot?

Occasional Contributor
Posts: 7

Re: Is it possible to show a regression line for specific data points?

Posted in reply to RobertAllison_SAS

gplot Smiley Happy

SAS Employee
Posts: 990

Re: Is it possible to show a regression line for specific data points?

Posted in reply to KageKitsune28

The built-in gplot interpol=rl regression line is going to always go all the way to the axis (I think).

If you just want the regression line to go to a certain point (and not all the way to the axis), then I think you'll need to calculate the points along the regression line (such as using Proc Reg), and then plot those points using interpol=join.

SAS Super FREQ
Posts: 1,227

Re: Is it possible to show a regression line for specific data points?

Posted in reply to RobertAllison_SAS

Or, just use SGPLOT.  Smiley Happy

data fit;
  do x2=1 to 8;
    y2=10+2*rannor(2); output;
  end;
  x2=.; y2=.;
  do x=9 to 10;
    y=10+2*rannor(2); output;
  end;
run;

proc sgplot data=fit;
  reg x=x2 y=y2 / name='r';
  scatter x=x y=y;
  keylegend 'r';
  run;

SAS Employee
Posts: 990

Re: Is it possible to show a regression line for specific data points?

Posted in reply to KageKitsune28

Similar to what Sanjay was saying about sgplot, you could also do this with gplot.

See the 'Forecast Line' example, near the middle of this Line Plot chapter for an example:

http://robslink.com/SAS/book1/Chapter_02_Lines.pdf

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