FAQ.md

@@ -160,8 +160,26 @@ All intermediate data processing steps (e.g. filtering, cropping) of the periphe
 For a detailed list of all properties and their documentation, read the source code of `tapas_physio_new.m`
 
 
-10. I cannot find the answer to my question in the FAQ. Whom do I ask for help?
+10. What is the order of the regressor columns in the multiple regressors file?
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+
+This depends on the physiological models (and their order) specified in the `model`-submodule of physio (or in the batch editor). The general order is outlined in Fig. 7A of the  [http://dx.doi.org/10.1016/j.jneumeth.2016.10.019](Main PhysIO Toolbox Paper). The []-brackets indicate the number of regressors:
+
+1. RETROICOR cardiac regressors [2 x nOrderCardiac]
+2. RETROICOR respiratory regressors [2 x nOrderRespiratory]
+3. RETROICOR cardXResp interaction regressors [4 x nOrderCardiacXRespiratory]
+4. HRV [nDelaysHRV]
+5. RVT [nDelaysRVT]
+6. Noise ROIs (PCA signatures and mean of each region) [nNoiseROIs x (nComponents+1)]
+7. Other (included other text file) [nColumnsOtherFile]
+8. Motion [6 or 12 or 24, depending on motion model]
+
+If any of the models was not specified, the number of regressors is reduced accordingly.
+
+
+11. I cannot find the answer to my question in the FAQ. Whom do I ask for help?
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+
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