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sdm-help-list > What does the size of the SDM value indicate?
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May 25, 2015 06:05 AM | Nobody
What does the size of the SDM value indicate?
Hi
Does the size of the SDM value given for a specific cluster indicate the relative difference between groups? If so, is there a standardised way to classify something as a small or large difference based on SDM values?
Thanks in advance for any help
Does the size of the SDM value given for a specific cluster indicate the relative difference between groups? If so, is there a standardised way to classify something as a small or large difference based on SDM values?
Thanks in advance for any help
Jun 3, 2015 08:06 AM | Nobody
RE: What does the size of the SDM value indicate?
Hi,
Cohen's effect size (i.e. the one used by SDM) may be conventionally classified in small (~0.2), medium (~0.5) and large (~0.8), with this classification being conventional and slightly varying from book to book.
That said, it is important to note that the use of peak information instead of SPM images currently biases the effect size towards zero, i.e. the reported SDM value is smaller than the true effect size.
Hope this helps,
Joaquim
Cohen's effect size (i.e. the one used by SDM) may be conventionally classified in small (~0.2), medium (~0.5) and large (~0.8), with this classification being conventional and slightly varying from book to book.
That said, it is important to note that the use of peak information instead of SPM images currently biases the effect size towards zero, i.e. the reported SDM value is smaller than the true effect size.
Hope this helps,
Joaquim