Hi, Steve
Thank you very much for the information
Longchuan
----- Original Message -----
From: "Steve Smith" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Wednesday, June 04, 2008 1:27 AM
Subject: Re: [FSL] about statistics for three groups
> Hi - a 3-group (e.g. 3-EV) simple GLM modelling will allow simple
> voxelwise ("univariate") testing between the groups.
>
> If you want to look for group effects interacting over multiple voxels
> then yes you'll need a multivariate test. For example, you can feed
> TBSS-preprocessed data into MELODIC.
>
> Cheers.
>
>
>
> On 4 Jun 2008, at 00:11, Longchuan Li wrote:
>
>> Hi Steve
>>
>> Sorry for the confusion I brought in the previous mail.
>>
>> My situation is like this: I have three groups: control, grp1, which has
>> the subjects with severe disease A, and grp2, which include subjects
>> with less severe degree of disease A. Also, for each group, there are
>> six region of interests. The aim of this analysis is to find out which
>> group is significantly different from the other groups. So, my questions
>> are like this:
>>
>> 1) if it is necessary to use multivariate tests to find out the
>> relations among different ROIs?
>>
>> 2) After ANOVA (or MANOVA), if it is necessary to use multiple
>> comparison correction?
>> One opinion is that it is not, as it usually has less sensitivity and
>> pair wise comparison between each pair should be enough; However, I
>> tried both and found that the results with and without multiple
>> comparison corrections are quite different, indicating the differences
>> among groups might not be very significant.
>>
>> I really want to hear some suggestions on this kind of analysis
>>
>> Your help is greatly appreciated
>>
>> Longchuan
>>
>> ----- Original Message ----- From: "Steve Smith" <[log in to unmask]>
>> To: <[log in to unmask]>
>> Sent: Tuesday, June 03, 2008 3:44 PM
>> Subject: Re: [FSL] about statistics for three groups
>>
>>
>>> Hi - I'm not quite sure what you're asking - but yes you can put 3
>>> groups into TBSS without problem.
>>> Cheers.
>>>
>>>
>>> On 3 Jun 2008, at 17:39, Longchuan Li wrote:
>>>
>>>> Hi Steve,
>>>> Thank you for the reply. Also, if I use these three groups to do TBSS
>>>> analysis, instead of ROI, do I still need to separate them instead of
>>>> putting them together?
>>>>
>>>> Thank you
>>>>
>>>> Longchuan Li
>>>> ----- Original Message ----- From: "Steve Smith" <[log in to unmask]
>>>> >
>>>> To: <[log in to unmask]>
>>>> Sent: Tuesday, June 03, 2008 3:34 AM
>>>> Subject: Re: [FSL] about statistics for three groups
>>>>
>>>>
>>>>> Hi,
>>>>>
>>>>> I would just run separate (t-test) comparisons for each pair of
>>>>> groups - this is sensitive to any group differences and very easy
>>>>> to interpret.
>>>>>
>>>>> Cheers.
>>>>>
>>>>>
>>>>>
>>>>> On 2 Jun 2008, at 18:46, Longchuan Li wrote:
>>>>>
>>>>>> Dear FSL experts
>>>>>>
>>>>>> I have a question regarding the statistics of multiple group
>>>>>> analysis. Right now, I have three groups, group 1 has the patients
>>>>>> with the most severe state of disease A (grp1), group 2 has the
>>>>>> patients with less significant degree of disease A (grp2) and group
>>>>>> 3 are unexposed controls (grp3). What is the best statistics if I
>>>>>> want to see the differences among the three groups? i.e., if grp1
>>>>>> and grp2 are significant different from grp3 and if there is
>>>>>> difference between grp1 and grp2.
>>>>>>
>>>>>> I am using one-way ANOVA to find out if there is any difference
>>>>>> among three groups and then use multiple comparison to pick out
>>>>>> which group is different. But I was also suggested that two sample
>>>>>> t tests between each group might be a better choice.
>>>>>>
>>>>>> Your help is greatly appreciated.
>>>>>>
>>>>>> Longchuan
>>>>>>
>>>>>
>>>>>
>>>>> ---------------------------------------------------------------------------
>>>>> Stephen M. Smith, Professor of Biomedical Engineering
>>>>> Associate Director, Oxford University FMRIB Centre
>>>>>
>>>>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>>>>> +44 (0) 1865 222726 (fax 222717)
>>>>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>>>>> ---------------------------------------------------------------------------
>>>>>
>>>>>
>>>>
>>>
>>>
>>> ---------------------------------------------------------------------------
>>> Stephen M. Smith, Professor of Biomedical Engineering
>>> Associate Director, Oxford University FMRIB Centre
>>>
>>> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
>>> +44 (0) 1865 222726 (fax 222717)
>>> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
>>> ---------------------------------------------------------------------------
>>>
>>>
>>
>
>
> ---------------------------------------------------------------------------
> Stephen M. Smith, Professor of Biomedical Engineering
> Associate Director, Oxford University FMRIB Centre
>
> FMRIB, JR Hospital, Headington, Oxford OX3 9DU, UK
> +44 (0) 1865 222726 (fax 222717)
> [log in to unmask] http://www.fmrib.ox.ac.uk/~steve
> ---------------------------------------------------------------------------
>
>
>
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