Hi guys,
just wanted to add a related comment.
People are increasingly starting to take more than one parameter
estimate per subject to the second level (e.g. HRF+derivatives). In this
case the sensitivity/specificity of the results will depend crucially on
the outcome of the estimation of the variance components, but at the
present time there isn't really any readily avilable information that
can be used to report in a paper.
I am guessing that the weights of "covariance-matrix-basis-functions"
are slightly to esoteric for most people (certainly is for me).
So, Karl/Will would it be possible to calculate also the corresponding
Greenhouse-Geiser correction factor, not for actual use on the data, but
for giving an intuitively interpretable number that can be used for
reporting?
Puss Jesper
> Max,
>
> > Is anyone aware of papers about presenting results for fMRI studies?
> > Specifically I'm looking for any attempts that have been made to
> > standardize what is reported and how.
>
> I don't know of any such efforts, but I think it's badly needed. I
> was once asked by an editor for such standards and started to make a
> list of statistical and non-statistical issues. I'd love to hear
> comments on such guidlines.
>
> -Tom
>
>
> -- Thomas Nichols -------------------- Department of Biostatistics
> http://www.sph.umich.edu/~nichols University of Michigan
> [log in to unmask] 1420 Washington Heights
> -------------------------------------- Ann Arbor, MI 48109-2029
>
>
> All papers should give sufficient detail so that if the reader were
> armed with the authors' data they could reproduce the results. Some
> important items:
>
> 1. What voxel-wise statistic image threshold was used? Corrected or
> uncorrected? FWE or FDR?
>
> 2. Was cluster size inference used? If so, what is the
> cluster-defining statistic image threshold? What is the cluster
> size threshold (in voxels) and significance (corrected or
> uncorrected).
>
> 3. How many voxels corrected for? Whole brain voxel count, or
> sub-volume count for 'Small Volume Correction'. If small volume
> correction, define how the sub-region was defined.
>
> 4. If random field theory is used, what is the smoothness (FWHM,
> x,y,z)? What is the RESEL count? (This allows one to independly
> recompute the corrected threshold)
>
>
> Not directly related to the statistics, but crucial for any complete
> reporting are:
>
> a. Basic image properties: image dimensions and voxel size.
> Properities of data as acquired *and* after intersubject
> registration (aka Spatial Normalization). For PET/SPECT, image
> reconstruction smoothness parameter (e.g. 'ramp filtered', 'Hanning
> filter, *** mm cutoff').
>
> b. Was slice timeing correction used?
>
> c. Smoothing applied. At 1st level and 2nd level if done twice.
>
> d. Basic intrasubject registration info. What software, what sort of
> interpolation.
>
> e. Basic itersubject registration parmaeters. Affine/Linear? If so,
> how many parameters (9 or 12, typically). If Nonlinear, 'how'
> nonlinear? (E.g. with AIR, you specify a polynomial order; with
> SPM, you specify a basis size, like 3x2x3). Regularization
> setting. What interpolation?
>
>
> This may sound like a lot, but they are all very basic parameters and
> can be concisely reported. They also can be reported in detail in one
> publication from a lab and then cite that publication for details that
> haven't changed.
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