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These are examples that have been worked out by creating FreeSurfer Group Descriptor (FSGD) files and contrasts for testing various hypotheses. These are not meant to be exhaustive, nor are they meant to teach you statistics. See these [[https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial?action=AttachFile&do=view&target=freesurfer.groupanalysis.ppt|slides]] for more of the statistics background on group analysis and how it applies to FreeSurfer. An alternative to constructing your own FSGD files is to use [[FsTutorial/QdecGroupAnalysis|QDEC]], though QDEC cannot be used with more than four groups and/or more than two continuous variables. |
These are examples of FreeSurfer Group Descriptor (FSGD) files and contrasts for testing various hypotheses. FreeSurfer can '''automatically''' construct design matrices from an FSGD file. The FSGD file is usually easier to construct than the design matrix. These examples are not meant to be exhaustive, nor are they meant to teach you statistics. See these [[https://surfer.nmr.mgh.harvard.edu/fswiki/FsTutorial?action=AttachFile&do=view&target=freesurfer.groupanalysis.ppt|slides]] for more of the statistics background on group analysis and how it applies to FreeSurfer. An alternative to constructing your own FSGD files is to use [[FsTutorial/QdecGroupAnalysis|QDEC]], though QDEC cannot be used with more than four groups and/or more than two continuous variables. |

These are examples of FreeSurfer Group Descriptor (FSGD) files and contrasts for testing various hypotheses. FreeSurfer can **automatically** construct design matrices from an FSGD file. The FSGD file is usually easier to construct than the design matrix.

These examples are not meant to be exhaustive, nor are they meant to teach you statistics. See these slides for more of the statistics background on group analysis and how it applies to FreeSurfer. An alternative to constructing your own FSGD files is to use QDEC, though QDEC cannot be used with more than four groups and/or more than two continuous variables.

One Group, Zero Covariates (OSGM = One-Sample Group Mean). DODS or DOSS

Two Groups (1 Factor, Two Levels), Zero Covariates. DODS or DOSS

Two Groups (1 Factor, Two Levels), One Covariate. DODS only.

Two Groups (1 Factor, Two Levels), Two Covariates. DODS only.

Three Groups (1 Factor, Three Levels), Zero Covariates. DODS or DOSS.

Four Groups (2 Factors, Two Levels), Zero Covariates. DODS or DOSS.

Four Groups (2 Factors, Two Levels), One Covariate. DODS only.

Six Groups (2 Factors, Three Levels), Zero Covariate. DODS or DOSS.