[R-meta] Questions about the use of metaprop for the pooling of proportions

[Dr. Gerta Rücker]

Dear Thiago, dear Michael,

I read this thread and I still am not clear about the nature of the 
data. Are these really compositional data, or simple proportions? The 
difference is:

  * Compositional data are characterized by lacking a denominator (no
    "n", no sample size). For each study, you have only percentages that
    add to 100%. Such data occur in microbioma research (percentages of
    species in the microbioma).
  * By contrast, proportions are given as r (number of events) and n
    (sample size, i.e., number of persons/patients/trials/whatever), or
    as percentages and n.

If you have proportions, you may use metaprop. If you have compositional 
data, as Michael supposed, you cannot.

Best,

Gerta

Am 08.03.2022 um 12:34 schrieb Thiago Roza:
> Dear Michael,
>
> Thank you for your reply!
>
> Do you think it would be possible to generate pooled proportions for
> at least the most commonly reported suicide method in this case? (I
> would organize my dataset in the following format: "suicide by
> hanging" vs "other method of suicide", only two categories).
>
> Thank you,
>
> Thiago
>
> Em seg., 7 de mar. de 2022 às 13:40, Michael Dewey
> <lists using dewey.myzen.co.uk> escreveu:
>> Dear Thiago
>>
>> What you have is compositional data which might prove a useful search
>> term. A common way to analyse such data is by taking the ratios of the
>> components to a reference one and then taking logs. However that is
>> about the sum total of my knowledge of compositional data analysis and
>> as far as I know there is no extant R package which deals with it.
>> Others on the list may have better ideas.
>>
>> For future reference if you post on CrossValidated it is best to put a
>> link in each of them so people can check if it has already been answered
>> in the other place.
>>
>> Michael
>>
>> On 06/03/2022 16:36, Thiago Roza wrote:
>>> Dear all,
>>>
>>> I am conducting a meta-analysis about characteristics of suicide
>>> deaths in post-mortem studies. My aim is to describe pooled
>>> proportions of key characteristics (biological sex, suicide site,
>>> race, marital status, suicide method, the proportion of substance use
>>> near death, proportion of psychiatric diagnosis prior to death, etc)
>>> across the included studies. Initially, I thought that "metaprop" from
>>> the package "meta" would be enough to pool all these proportions
>>> across included studies. Nevertheless, some of these variables have
>>> more than one category (i.e. suicide method has more than 10
>>> categories: such as hanging, firearm, poisoning, etc), and the pooling
>>> of the proportion of each suicide method separately produces results
>>> which when summed up give more than 100% for the summed proportion of
>>> all suicide methods. Therefore, my first question is: is it possible
>>> to pool all those proportions using "metaprop"? If yes, could anyone
>>> give an example about the coding for the pooling of proportions in the
>>> case of suicide methods? If not, is there any other package that would
>>> allow me to pool the aggregate proportion of suicide methods?
>>>
>>> Thank you,
>>>
>>> Thiago Roza
>>>
>>> _______________________________________________
>>> R-sig-meta-analysis mailing list
>>> R-sig-meta-analysis using r-project.org
>>> https://stat.ethz.ch/mailman/listinfo/r-sig-meta-analysis
>>>
>> --
>> Michael
>> http://www.dewey.myzen.co.uk/home.html
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-- 

Dr. rer. nat. Gerta Rücker, Dipl.-Math.

Guest Scientist
Institute of Medical Biometry and Statistics,
Faculty of Medicine and Medical Center - University of Freiburg

Zinkmattenstr. 6a, D-79108 Freiburg, Germany

Mail:     ruecker using imbi.uni-freiburg.de
Homepage: https://www.uniklinik-freiburg.de/imbi-en/employees.html?imbiuser=ruecker


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