PowerPoint Presentation - Time Series Analysis in AFNI

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Deconvolution: Pros and Cons

+ Letting HRF shape varies allows for subject and regional variability in hemodynamics

+ Can test HRF estimate for different shapes; e.g., are later time points more “active” than earlier?

– Need to estimate more parameters for each stimulus class than a fixed-shape model (e.g., 4-15 vs. 1 parameter=amplitude of HRF)

– Which means you need more data to get the same statistical power (assuming that the fixed-shape model you would otherwise use was in fact “correct”)

– Freedom to get any shape in HRF results can give weird shapes that are difficult to interpret