Thank you very much for your illustration, Wolfgang! It helped me a lot.
And also thank you for the package-hint, Michael!

Now, I have re-checked the respective studies, and there still are a couple
of studies left, only stating cohens d, and the respective t-value and
p-value - sample and group sizes are not addressed (its data from an older
meta-analysis). Is there a way to embed these studies in my sample?
Wolfgangs illustration addresses only cases in which group sizes are
stated, if I understand you correctly...

Many thanks in advance,

Verena


On Sat, Apr 26, 2014 at 1:38 PM, Michael Dewey <info@aghmed.fsnet.co.uk>wrote:

> At 20:34 25/04/2014, Viechtbauer Wolfgang (STAT) wrote:
>
>> If you know the d-value and the corresponding group sizes for a study,
>> then it's possible to add that study to the rest of the dataset. Also, if
>> you only know the test statistic from an independent samples t-test (or
>> only the p-value corresponding to that test), it's possible to back-compute
>> what the standardized mean difference is.
>>
>> I added an illustration of this to the metafor package website:
>>
>> http://www.metafor-project.org/doku.php/tips:assembling_data_smd
>>
>
> Verena might also like to look at the compute.es package available from
> CRAN to see whether any of the conversions programmed there do the job.
>
>
>
>  Best,
>> Wolfgang
>>
>> --
>> Wolfgang Viechtbauer, Ph.D., Statistician
>> Department of Psychiatry and Psychology
>> School for Mental Health and Neuroscience
>> Faculty of Health, Medicine, and Life Sciences
>> Maastricht University, P.O. Box 616 (VIJV1)
>> 6200 MD Maastricht, The Netherlands
>> +31 (43) 388-4170 | http://www.wvbauer.com
>>
>> > -----Original Message-----
>> > From: r-help-bounces@r-project.org [mailto:r-help-bounces@r-project.org
>> ]
>> > On Behalf Of Michael Dewey
>> > Sent: Friday, April 25, 2014 16:23
>> > To: Verena Weinbir
>> > Cc: r-help@r-project.org
>> > Subject: Re: [R] Metafor: How to integrate effectsizes?
>> >
>> > At 12:33 25/04/2014, you wrote:
>> > >Thank you very much for your reply and the book recommendation,
>> Michael.
>> > >
>> > >Yes, I mean Cohen's d - sorry for the typo :-)
>> > >
>> > >Just to make this sure for me: There is no
>> > >possibility to integrate stated Cohens' ds in an
>> > >R-Metaanalysis (or a MA at all), if there is no
>> > >further information traceable regarding SE or the like?
>> >
>> > If there is really no other information like
>> > sample sizes, significance level, value of some
>> > significance test then you would have to impute a
>> > value from somewhere. That would seem a last resort.
>> >
>> > I have cc'ed this back to the list, please keep
>> > it on the list so others may benefit and contribute.
>> >
>> >
>> > >best regards,
>> > >
>> > >Verena
>> > >
>> > >
>> > >On Fri, Apr 25, 2014 at 1:21 PM, Michael Dewey
>> > ><<mailto:info@aghmed.fsnet.co.uk>info@aghmed.fsnet.co.uk> wrote:
>> > >At 13:15 24/04/2014, Verena Weinbir wrote:
>> > >Hello!
>> > >
>> > >I am using the metafor package for my master's thesis as an R-newbie.
>> > While
>> > >calculating effectsizes from my dataset (mean values and
>> > >standarddeviations) using "escalc" shouldn't be a problem (I hope ;-)),
>> > I
>> > >wonder how I could at this point integrate additional studies, which
>> > only
>> > >state conhens d (no information about mean value and sds available), to
>> > >calculate an overall analysis. Â I would be very grateful for your
>> > support!
>> > >
>> > >
>> > >You mean Cohen's d I think.
>> > >
>> > >You will need some more information to enable
>> > >you to calculate its standard error. Have a look at Rosenthal's chapter
>> > in
>> > >@book{cooper94,
>> > >Â  Â author = {Cooper, H and Hedges, L V},
>> > >Â  Â title = {A handbook of research synthesis},
>> > >Â  Â year = {1994},
>> > >Â  Â publisher = {Russell Sage},
>> > >Â  Â address = {New York},
>> > >Â  Â keywords = {meta-analysis}
>> > >}
>> > >(There is an updated edition)
>> > >This gives you more information about converting
>> > >effect sizes and extracting them from unpromising beginnings.
>> > >
>> > >It often requires some ingenuity to get the
>> > >information you need so have a go and then get
>> > >back here with more details if you run into problems
>> > >
>> > >
>> > >Best regards,
>> > >
>> > >Verena
>>
>
> Michael Dewey
> info@aghmed.fsnet.co.uk
> http://www.aghmed.fsnet.co.uk/home.html
>
>

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