# Thread: How to draw standard deviation in a plot.

1. ## How to draw standard deviation in a plot.

Hello,
I have run 10 different experiments. In each of these ten experiments only the value X of one parameter is changed.

What I would like to do is to plot the mean values of these experiments in the same plot.

The x value is for the X variable that is changed every time. What I would like to show is: how the changes of variable X affect the mean value of the ten different experiments.

So I have just to put some marks which is easy. What I would like also to do is to plot somehow to the mean values their standard deviations. So could you please how I can do that? How to add std close to the mean?

Best Regards
Alex.

2. Originally Posted by dervast
Hello,
I have run 10 different experiments. In each of these ten experiments only the value X of one parameter is changed.

What I would like to do is to plot the mean values of these experiments in the same plot.

The x value is for the X variable that is changed every time. What I would like to show is: how the changes of variable X affect the mean value of the ten different experiments.

So I have just to put some marks which is easy. What I would like also to do is to plot somehow to the mean values their standard deviations. So could you please how I can do that? How to add std close to the mean?

Best Regards
Alex.
Box and Whisker plot?
CB

3. Originally Posted by CaptainBlack
Box and Whisker plot?
CB
Thanks a lot!
So, This is what I have to do
http://en.wikipedia.org/wiki/File:Boxplot_vs_PDF.png

Is that right?

4. Originally Posted by dervast
Thanks a lot!
So, This is what I have to do
File:Boxplot vs PDF.png - Wikipedia, the free encyclopedia

Is that right?
It is not quite what you asked for as it shows quartiles rather than standard deviations, but I think it does the sort of thing you asked for.

CB

5. Originally Posted by CaptainBlack
It is not quite what you asked for as it shows quartiles rather than standard deviations, but I think it does the sort of thing you asked for.

CB
Thanks a lot! But how to put std then? Std relates somehows to quartiles so if i calculate the quartiles probably is not that good but still is something.

6. Originally Posted by dervast
Thanks a lot! But how to put std then? Std relates somehows to quartiles so if i calculate the quartiles probably is not that good but still is something.
If you really want SD's in the plot instead of the quartiles use +/-1 and 2 SD's (but lable the plot so people know what you have done).

(There are good reasons for prefering the quartiles - they are less effected by outliers than the SD).

CB