RE: st: graphing median values against time

[Timothy Mak <tshmak@hku.hk>]

<>
Thanks Nick very much for helping to answer my question. 

To plot more than one summary statistics is a bit difficult, and you do have to use the -addplot- and the -alsocollapse- options. If you hadn't specified -by(aborig)-, then Nick's syntax would be almost right, except that you don't need the -if bvisittm1N- in the end, i.e. -addplot(line median bvisittm1N)- would do. However, because you have specified -by(aborig)-, you really need to do: 

addplot(line median bvisittm1N if aborig == 1 || line median bvisittm1N if aborig == 2)

supposing your variable aborig has 2 levels (1,2). 

To understand the use of the -addplot- and the -alsocollapse- option a bit more, you may want to use the -nopreserve- option. This gives you the dataset that -lgraph- actually uses to plot your graph. Also, have a look at the macros `r(command)' and `r(options)'. This gives you the -twoway- syntax that lgraph uses on the collapsed data. Be sure to use command double quotes though when you display the macros, i.e.: 

di `"`r(command)'"'
di `"`r(options)'"'

I hope that helps. 

Tim


-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: 31 March 2014 08:38
To: statalist@hsphsun2.harvard.edu
Subject: Re: st: graphing median values against time

You *must* specify a -twoway- subcommand, not -lgraph-, in the
-addplot()- call. This is documented in the help for -addplot option-.

I doubt very much that giving the same variable names as in the main
call will do what you want.

My second guess is that you need something more like

alsocollapse((median) median=totend28)
addplot(line median bvisittm1N if bvisittm1N)

Nick
njcoxstata@gmail.com


On 31 March 2014 01:29, Donald Spady <dspady@ualberta.ca> wrote:
> Nick
> I had tried various combinations of that command and could not get it to work.
>
>   here is my command
> .lgraph tottend28  bvisittm1N if bvisittm1N < 55, by(aborig) xlabel(0(3)54) stat(mean)  alsocollapse((median)) addplot(lgraph tottend28  bvisittm1N if bvisittm1N <55, by(aborig))
>
> It doesn't work.  I get the error
> lgraph is not a twoway plot type
> r(198);
>
> Don
> On Mar 30, 2014, at 5:14 PM, Nick Cox <njcoxstata@gmail.com> wrote:
>
>> Timothy explains how to do that in the help.
>>
>>    addplot(plot) This allows additional twoway plots to be plotted.
>> See addplot_option. Note that
>>        because lgraph collapses the data before plotting in twoway,
>> plots given in addplot(plot)
>>        should also refer to the collapsed data. Specify in
>> alsocollapse(clist) any additional data
>>        that need to be collapsed.
>>
>> So, if you want median as well as mean you must specify
>>
>> alsocollapse(median) addplot(<whatever>)
>>
>> Note that nothing obliges you to use another -line- call.
>>
>> I haven't use -lgraph-, just looked at its help, but Timothy provides
>> lots of functionality.
>> Nick
>> njcoxstata@gmail.com
>>
>>
>> On 30 March 2014 23:51, Donald Spady <dspady@ualberta.ca> wrote:
>>> Timothy
>>>  I am using your -lgraph- command and wonder if it is possible to have TWO stats created (e.g. mean and median) for the same variable(s) at the same time.  I want to plot both mean and median and cannot create an overlay to do so.
>>>
>>> Many thanks
>>> Don
>>> On Mar 28, 2014, at 1:29 AM, Timothy Mak <tshmak@hku.hk> wrote:
>>>
>>>> The command -lgraph- that I wrote is for exactly this kind of problem if you don't want to create all the variables before plotting a graph.
>>>> You can see it by typing:
>>>> ssc des lgraph
>>>>
>>>> Tim
>>>>
>>>> -----Original Message-----
>>>> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Donald Spady
>>>> Sent: 28 March 2014 08:59
>>>> To: Statalist Statalist
>>>> Subject: Re: st: graphing median values against time
>>>>
>>>> Nick
>>>> It works.  Just as I needed. Many thanks.
>>>> John: That suggestion didn't work the way I wanted it to, but thanks for the idea.
>>>>
>>>> Don
>>>> On Mar 27, 2014, at 5:48 PM, Nick Cox <njcoxstata@gmail.com> wrote:
>>>>
>>>>> Sure. If you use -egen-'s -median()- and -mean()- functions to get the
>>>>> variables you want, then it's any graph you want.
>>>>>
>>>>> As the median and mean values are repeated, don't plot them repeatedly.
>>>>>
>>>>> Here are some dopey examples.
>>>>>
>>>>> . webuse grunfeld
>>>>>
>>>>> . egen median = median(invest), by(year)
>>>>>
>>>>> . egen mean = mean(invest), by(year)
>>>>>
>>>>> . egen tag = tag(year)
>>>>>
>>>>> . line mean median year if tag
>>>>>
>>>>> For finer subdivisions, just use more variables as arguments to -by()-.
>>>>>
>>>>> Nick
>>>>> njcoxstata@gmail.com
>>>>>
>>>>>
>>>>> On 27 March 2014 22:34, Donald Spady <dspady@ualberta.ca> wrote:
>>>>>> Dear all
>>>>>> I want to graph the median and mean values of a series of variables against a time variable (on the X axis) and with the option of stratifying the variables by another one (such as sex or disease state).  I think I can do this by collapsing the data but is it possible to do this while retaining the data set in its 'original' state.  I have searched the archives and the reference manuals but have not come up with anything that seems to be what I want.
>>>>>> In many ways what I would like is a box plot with JUST the median (or mean) being plotted: no box, no outliers.  Is that possible.
>>>>>>
>>>>>> Thanks
>>>>>> Don
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