Early phonological development

[Bruno Estigarribia]

Nina,

Clearly, a rule of thumb like that provided by Barbara is useful. 
However, I would say the number of children, sampling frequency, and 
duration of each sample is mostly determined by the questions you want 
to ask and the kind of analysis you have in mind. It seems to me that 60 
minute samples are too long, unless (a) you want to highly increase your 
estimates' accuracy at each timepoint or (b) you are looking at 
infrequent variables. Or, if you were planning to use time series 
analysis, for instance, you may have enough with half the children and 
30 minute samples, because you'll need a lot more data points for each 
child. The bottomline is: now is when you need to plan your questions 
and analysis very carefully, and the answer will depend very directly on 
the particulars of your analysis plan.
And of course, another crucial thing is your recording equipment, but 
since you didn't ask about that, I assume you're all set!
Bruno Estigarribia
FPG Child Development Institute
Neurodevelopmental Disorders Research Center
UNC - Chapel Hill
> Dear Nina,
> I second the choice of 10 children.  The number you need, I believe, depends 
> on the variability in your measures, (which I suspect is pretty great in 
> early phonological measures), but I have found as a rule of thumb that 10 is 
> better than 7 and not usually much better than 12.  When I have done 
> preliminary analyses of groups before all the data were collected, group 
> means from 6 and 7 children were rarely within a standard error plus or 
> minus of the eventual group (of around 30), whereas groups of 10 almost 
> always were.  You might start out with a couple extra though to guard 
> against technical failures and non-cooperation--or hurricanes, in our case!
>
> Good luck,
> Barbara
> *************************************************************
> Barbara Zurer Pearson, Ph.D.
> Research Associate,
> Depts of Linguistics and Communication Disorders
> 226 South College
> University of Massachusetts
> Amherst MA 01003
>
> Tel: 413-545-5023
> Fax: 413-545-2792
>
> bpearson at research.umass.edu
> www.umass.edu/aae/bp_indexold.htm
> www.zurer.com/pearson
>
>
> ----- Original Message ----- 
> From: "Nina" <n.g.garmann at iln.uio.no>
> To: "Info-CHILDES" <info-childes at googlegroups.com>
> Sent: Thursday, May 22, 2008 5:50 AM
> Subject: Early phonological development
>
>
>   
>> Dear all,
>>
>> I am currently planning a three year post doctor project on the early
>> phonological development of Norwegian children. I find it difficult to
>> determine the appropriate number of children for this study. My
>> current plan is to compile data from one-hour play sessions with 10
>> children every six weeks for six months (18, 19.5, 21, 22.5, 24
>> months). Has anyone done a similar study or could anyone in other ways
>> supply me with any ideas concerning the number of participants,
>> session intervals or the six months period of data compilation?
>>
>> Regards, Nina G. Garmann
>>     
>
>
> >
>   


--~--~---------~--~----~------------~-------~--~----~
You received this message because you are subscribed to the Google Groups "Info-CHILDES" group.
To post to this group, send email to info-childes at googlegroups.com
To unsubscribe from this group, send email to info-childes-unsubscribe at googlegroups.com
For more options, visit this group at http://groups.google.com/group/info-childes?hl=en
-~----------~----~----~----~------~----~------~--~---