Example of second level design matrix#
This example shows how a second-level design matrix is specified: assuming that the data refer to a group of individuals, with one image per subject, the design matrix typically holds the characteristics of each individual.
This is used in a second-level analysis to assess the impact of these characteristics on brain signals.
This example requires matplotlib.
try: import matplotlib.pyplot as plt except ImportError: raise RuntimeError("This script needs the matplotlib library")
Create a simple experimental paradigm#
We want to get the group result of a contrast for 20 subjects.
Next, we specify extra information about the subjects to create confounders. Without confounders the design matrix would correspond to a one sample test.
Create a second level design matrix#
With that information we can create the second level design matrix.
/usr/share/miniconda3/envs/testenv/lib/python3.9/site-packages/nilearn/glm/first_level/design_matrix.py:476: UserWarning: Attention: Design matrix is singular. Aberrant estimates are expected.
Let’s plot it.
Total running time of the script: ( 0 minutes 1.474 seconds)
Estimated memory usage: 9 MB