<div dir="ltr"><div>Hi Julian </div><div><br></div><div>I indeed meant comparing within subject conditions, one with many more trials than the other (e.g. 500 vs 100 trials). I am aware that this difference would bias my result, the question is whether there might be a way to bypass such bias, without the conservative solution of equating the trial number in both conditions (i.e. removing 400 trials from condition1, and thereby comparing 100 vs 100). </div><div>One possible solution that was suggested was to proceed with an indepT test, and then proceeding with an "spm_t2z" transformation ; yet, I wonder whether this is also valid for such large difference between sample sizes. </div><div><br></div><div>Thanks</div><div>Yoni</div><div><br></div><div class="gmail_extra"><br><div class="gmail_quote">On Thu, Jan 22, 2015 at 1:00 PM, <span dir="ltr"><<a href="mailto:fieldtrip-request@science.ru.nl" target="_blank">fieldtrip-request@science.ru.nl</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Send fieldtrip mailing list submissions to<br>
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Today's Topics:<br>
<br>
1. Statistics: comparing conditions with different sample size<br>
(Yoni Levy)<br>
2. Re: Statistics: comparing conditions with different sample<br>
size (Julian Keil)<br>
<br>
<br>
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Message: 1<br>
Date: Thu, 22 Jan 2015 08:54:07 +0200<br>
From: Yoni Levy <<a href="mailto:yoniilevy@gmail.com">yoniilevy@gmail.com</a>><br>
To: <a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a><br>
Subject: [FieldTrip] Statistics: comparing conditions with different<br>
sample size<br>
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<br>
Is there a way in FT to deal with the statistical comparison of conditions<br>
with different sample size (for instance N = 500 vs N = 100)?<br>
<br>
Thanks for any input<br>
Yoni<br>
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Message: 2<br>
Date: Thu, 22 Jan 2015 09:05:20 +0100<br>
From: Julian Keil <<a href="mailto:julian.keil@gmail.com">julian.keil@gmail.com</a>><br>
To: FieldTrip discussion list <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br>
Subject: Re: [FieldTrip] Statistics: comparing conditions with<br>
different sample size<br>
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<br>
Dear Yoni,<br>
<br>
do you mean different *group* sizes (as in 500 patients vs. 100 controls)? Then use the stat fun indepsamplesT.<br>
If you mean 500 trials vs 100 trials within one subject, you can again use the indepsamplesT-function, but beware! The number of trials can severely influence your signal.<br>
I personally strongly suggest using the same number of trials and subjects.<br>
<br>
Best,<br>
<br>
Julian<br>
<br>
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********************<br>
Dr. Julian Keil<br>
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AG Multisensorische Integration<br>
Psychiatrische Universit?tsklinik<br>
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Am 22.01.2015 um 07:54 schrieb Yoni Levy:<br>
<br>
> Is there a way in FT to deal with the statistical comparison of conditions with different sample size (for instance N = 500 vs N = 100)?<br>
><br>
> Thanks for any input<br>
> Yoni<br>
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