Hi all

Yes - I've discussed this with Todd and it's not immediately clear whether the 
difference is due to:
 - they used full correlation not partial
 - they used fewer confound regressors (IIRC)
 - their prediction method is *very* different (pooling across all relevant 
features rather than keeping them separate in the multivariate elastic net 
regression prediction).

Or some combination of all of this.  I don't have a strong gut feeling which of 
these might be the biggest factor, but we should note that the Finn paper took 
a lot more care over many aspects of their analysis than many studies do, and 
in particular it was impressive how they got replication of the prediction 
between completelty separate studies. But yes I would be interested to see this 
resolved more.

With respect to our CCA-based population mode, which covaried more highly with 
the intelligence measure as you mentioned - I think maybe this points at the 
main issue possibly being the noisiness of the individual features (netmat 
edges) and also of the intelligence feature (when all combined together within 
the elastic net prediction framework).

Cheers.




> On 6 Oct 2017, at 04:11, Harms, Michael <[email protected]> wrote:
> 
>  
> In the context of the long resting state runs that we have available, I would 
> argue that throwing in additional possible confounds is the appropriate thing 
> to do.  Are you suggesting that sex, age, age^2, sex*age, sex*age^2, brain 
> size, head size, and average motion shouldn’t all be included?
>  
> Regardless, r = 0.21 (without confounds in the MegaTrawl) is a long way from 
> the r = 0.5 prediction in Finn et al.
>  
> Cheers,
> -MH
>  
> -- 
> Michael Harms, Ph.D.
> -----------------------------------------------------------
> Conte Center for the Neuroscience of Mental Disorders
> Washington University School of Medicine
> Department of Psychiatry, Box 8134
> 660 South Euclid Ave.                        Tel: 314-747-6173
> St. Louis, MO  63110                                          Email: 
> [email protected] <mailto:[email protected]>
>  
> From: <[email protected] 
> <mailto:[email protected]>> on behalf of Thomas Yeo 
> <[email protected] <mailto:[email protected]>>
> Date: Thursday, October 5, 2017 at 10:01 PM
> To: "Glasser, Matthew" <[email protected] <mailto:[email protected]>>
> Cc: "[email protected] <mailto:[email protected]>" 
> <[email protected] <mailto:[email protected]>>
> Subject: Re: [HCP-Users] netmats prediction of fluid intelligence
>  
> Certainly one difference is that HCP (i.e., Steve) tends to take the more 
> conservative approach of regressing a *lot* of potential confounds, which 
> tends to result in a lower prediction values. You can see that without 
> confound regression, Steve's prediction is 0.21 versus 0.06. 
>  
> Regards,
> Thomas
>  
> On Fri, Oct 6, 2017 at 1:44 AM, Glasser, Matthew <[email protected] 
> <mailto:[email protected]>> wrote:
>> Perhaps there is an issue related to data clean up or alignment of brain 
>> areas across subjects.  The Finn study does not appear to have followed the 
>> recommended approach to either.
>>  
>> Peace,
>>  
>> Matt.
>>  
>> From: <[email protected] 
>> <mailto:[email protected]>> on behalf of Benjamin Garzon 
>> <[email protected] <mailto:[email protected]>>
>> Date: Thursday, October 5, 2017 at 1:39 PM
>> To: "[email protected] <mailto:[email protected]>" 
>> <[email protected] <mailto:[email protected]>>
>> Subject: [HCP-Users] netmats prediction of fluid intelligence
>>  
>> Dear HCP experts, 
>>  
>> I'm trying to reconcile the MegaTrawl prediction of fluid intelligence 
>> (PMAT24_A_CR)
>>  
>> https://db.humanconnectome.org/megatrawl/3T_HCP820_MSMAll_d200_ts2/megatrawl_1/sm203/index.html
>>  
>> <https://db.humanconnectome.org/megatrawl/3T_HCP820_MSMAll_d200_ts2/megatrawl_1/sm203/index.html>
>>  
>> (which shows r = 0.06 between predicted and measured scores)
>>  
>> with the Finn 2015 study 
>>  
>> https://www.nature.com/neuro/journal/v18/n11/full/nn.4135.html 
>> <https://www.nature.com/neuro/journal/v18/n11/full/nn.4135.html>
>>  
>> claiming an r = 0.5 correlation between predicted and measured scores. In 
>> the article they used a subset of the HCP data (126 subjects), but the 
>> measure of fluid intelligence is the same one. What can explain the 
>> considerable difference? As far as I can see the article did not address 
>> confounding, but even in that case r = 0.21 for MegaTrawl, which is still 
>> far from 0.5. And this considering that the model used in the article is a 
>> much simpler one than the MegaTrawl elastic net regressor.   
>>  
>> I've been trying to predict fluid intelligence in an independent sample with 
>> 300 subjects and a netmats + confounds model does not perform better than a 
>> confounds-only model, more in agreement with the MegaTrawl results. 
>>  
>> In the Smith 2015 paper 
>>  
>> http://www.nature.com/neuro/journal/v18/n11/full/nn.4125.html 
>> <http://www.nature.com/neuro/journal/v18/n11/full/nn.4125.html>
>>  
>> the found mode of covariation with the netmats data correlates with fluid 
>> intelligence with r = 0.38.
>>  
>> Should I conclude from the Megatrawl analysis (as well as from my own) that 
>> the single measure of fluid intelligence is not reliable enough to be 
>> predicted based on connectome data, or am I missing something from the Finn 
>> paper?
>>  
>> I would be happy to read people 's thoughts about this topic, in view of the 
>> disparate results in the literature. 
>>  
>> Best regards, 
>>  
>> Benjamín Garzón, PhD
>> Department of Neurobiology, Care Sciences and Society
>> Aging Research Center | 113 
>> <https://maps.google.com/?q=113%C2%A030+Stockholm+%7C+G%C3%A4vlegatan+16&entry=gmail&source=g>
>>  30 Stockholm | Gävlegatan 16 
>> <https://maps.google.com/?q=113%C2%A030+Stockholm+%7C+G%C3%A4vlegatan+16&entry=gmail&source=g>
>> [email protected] <mailto:[email protected]> | www.ki-su-arc.se 
>> <https://email.ki.se/owa/redir.aspx?C=LDNa9T7Nak68Br6ZyIC_J4KUwCiWMdEIQwVElfLYlCPLbdpUruOe0XhySwY-dNAYT9JyRT4AtFo.&URL=http%3a%2f%2fwww.ki-su-arc.se%2f>
>> ______________________________________
>> Karolinska Institutet – a medical university
>>  
>>  
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