topic Forest plot in Statistical Procedures

Forest plot

Ashwini_uci — Tue, 06 Mar 2012 01:00:48 GMT

ANy ideas about how to create a forest plot in SAS? or in Excel?

Here is the data that i have to plot the forest plot

This is how my plot looks like..

Forest plot

Rick_SAS — Tue, 06 Mar 2012 01:56:10 GMT

See this blog post: http://blogs.sas.com/content/graphicallyspeaking/2012/02/01/forest-plot-using-sgplot-procedure/

Forest plot

Doc_Duke — Tue, 06 Mar 2012 02:17:45 GMT

In addition to Rick's direct answer, if you go to support.sas.com and type in

"forest plot"

in the search box, you will find several different approaches to doing it in SAS.

Forest plot

Ashwini_uci — Wed, 14 Mar 2012 16:39:04 GMT

Thanks Rick for this, it helps. Is there also a way in Excel to do the forest plot?

Forest plot

Reeza — Wed, 14 Mar 2012 16:45:21 GMT

You need to calculate the data for the forest plot in Excel.

Basically, you create a scatterplot with error bars (google this and you'll find a lot of examples and detailed instructions). And add a reference line at 1 manually or with another series.

http://www.stattools.net/ForestPlot_Exp.php

About halfway down the page.

Forest plot

Ashwini_uci — Wed, 14 Mar 2012 17:08:45 GMT

Thanks Reeza for your response, Yes, I do have the data and i have already viisted the link that you have given here. I was stuck at the log scale conversion step and couldnot prooceed further, so still trying to look up for more help..

Forest plot

Reeza — Wed, 14 Mar 2012 17:17:14 GMT

What version of Excel do you have? In 2003 you right click your x axis>Format Axis>Scale at the bottom is the check box for log scale.

This depends on what the scale of your data is.

You can alos modify where the line is by changing the Value(Y) axis Crosses at in the same dialog box to 1 if you're doing OR plots.

Another and better option if your comparing OR's from SAS in my opinion is turning on ODS graphics for proc logistics. The default procedure will produce something similar to a forest plot. Obviously this isn't appropriate if you're doing a meta analysis.

Forest plot

Ashwini_uci — Wed, 14 Mar 2012 17:34:18 GMT

I have attached the data in the original post now. Please have a look at it.. somehow , the graph only hows UCL and OR. and shows LCL only for one data point. Somehting is wrong there.

Mine is windows XP, excel 2003 , .

Forest plot

Ashwini_uci — Wed, 14 Mar 2012 17:43:10 GMT

now i have attached the file in which you can see how it looks like.. i tried it again, biut not sure why it is vertical and ot horizontal..

Any idea?

Forest plot

Reeza — Wed, 14 Mar 2012 17:51:27 GMT

Create a scatter plot of ONLY your OR and have the Y values be 1/2/3 etc, some count that puts them in the order you want to display and the OR along the X axis.

Change your graph to not show any gridlines, except the one at y=1

Calculate the +/- values for each arm (based on the CI you already have).

Add x error bars individually for each point based on the +/- bars

Right click on the error bars and format them to not have the end points.

A very very manual process in my opinion which is why SAS and SGPLOT are useful

Forest plot

Reeza — Thu, 15 Mar 2012 16:37:01 GMT

Not to get into too much detail, but what is an Overall Odds Ratio?

Forest plot

Ashwini_uci — Fri, 16 Mar 2012 16:44:22 GMT

Not sure what you mean by overall OR.

Forest plot

Ashwini_uci — Fri, 16 Mar 2012 16:52:01 GMT

Okay I understadn until step3.

For step 4, how do i add x error bars...not sure of that.

I have got 3 different ORs (with CI) after running 3 different Proc logistics. So even if i want to create the forest plot in SAS, how do i do that by turning on ODS graphic whie running any one of the proc logistic?

Forest plot

Reeza — Fri, 16 Mar 2012 16:53:09 GMT

Your example data has an Overall OR for female and male, what would that represent, how would you phrase that in a sentence?

ie if my OR is 3.4 (95% CI 2.5, 4.2) and the event is hospital admissions:

Females are 3.4 times more likely than males to have a hospital admission (95% CI 2.5, 4.2).

Or conversely, Males are 0.3 times as likely than females to have a hospital admission (95% CI 0.24,0.4)

Forest plot

Reeza — Fri, 16 Mar 2012 16:54:41 GMT

Right click points and Format Data Series, one of the tabs is X error bars.

Forest plot

Ashwini_uci — Fri, 16 Mar 2012 17:04:23 GMT

Great Reeza,.. this seems to work. I am almost there BUT NOW .. it is not letting me select one point at a time, I have 3 diff ORs with diff LCL and UCL. I am not able to select each point at a time and enter its LCL and UCL.. How do i do that?

And at what point should I change the scale to log scale.?

Forest plot

Ashwini_uci — Fri, 16 Mar 2012 21:30:24 GMT

Thanks som much Reeza, for helping me with this. But i have had any success yet to create this forest plot. Its just not letting me select each point at a time and enter its LCL and UCL.. How do i do that?

And at what point should I change the scale to log scale.?

Appreciate if you cvould guide me with this until its completion..

Forest plot

Ashwini_uci — Fri, 16 Mar 2012 21:31:05 GMT

**Have NOT had any success yet...

Re: Forest plot

Reeza — Sat, 17 Mar 2012 23:57:22 GMT

Here's an example.

I only have Excel 2010 at home so hopefully it works.

Good luck.

Forest plot

Ashwini_uci — Tue, 20 Mar 2012 20:07:34 GMT

Reeza, that was a Great help!! Really appreciate

I could finally plot all the forest plots using excel!!

Thanks a bunch!

Ashwini