![]() Let’s say that we observed which students showed an improvement, and then ran our final group-level analysis on only those students. To give an example of a biased analysis, imagine that we wanted to test whether drinking Four Loko helps undergraduates do better on their exams. Question: What is a biased analysis? How do you avoid doing them? As a result, the new square will now contain the value 8. In the upper left corner, for example, the number 8 is closest to the center of the new square. In the animation below, we superimpose a 3x3 grid on the original 4x4 grid and then find which number is closest to the center of the new square. Imagine that we have a 4x4 grid with a number in each square, and that we want to resample it to a 3x3 grid. Let’s start with the nearest neighbor method, which is the easiest to illustrate. You can resample an image using several different methods. Larger voxels lead to a lower-resolution image, and smaller voxels will lead to a higher-resolution image. One common use of resampling is to make the dimensions of the voxel either shorter or longer, which in turn creates larger or smaller voxels. Voxels can either be isotropic, with dimensions of equal lengths, or anisotropic, with at least one dimension either longer or shorter than the other dimensions. Each of these cubes contains a single number representing the signal measured at that voxel. Introduction to Tract-Based Spatial Statistics (TBSS)Īn fMRI image is composed of cubes called voxels (lower right).GIMME (Group Iterative Multiple Model Estimation).I get the message “ERROR: Could not resample” when running AFNI’s align_epi_anat.py.How do I extract the voxel coordinates for an ROI?.How do I merge multiple ROIs into a Single File?.Unwarping with blip-up/blip-down images.Step 2: Apply fieldmap with FUGUE to unwarp functional images.Step 0: Create brain mask of magnitude image.How can I calculate the number of voxels in a mask?.What is Signal-to-Noise Ratio? How can I calculate it?.fASL Tutorial #5: Examining the Results.fASL Tutorial #2: Downloading and Installing.Introduction to the Human Connectome Project.Introduction to the Human Connectome Project (HCP) Parametric Modulation in SPM, FSL, and AFNI.Functional Connectivity and the CONN Toolbox.fMRI Tutorial #5: Statistics and Modelingįunctional Connectivity with the CONN Toolbox.fMRI Tutorial #2: Overview of The Flanker Task.Unix Tutorial #9: Automating The Analysis.Unix Tutorial #6: Conditional Statements.Unix Tutorial #4: Shells and Path Variables.Unix Tutorial #2: Copying and Removing Files.Unix Tutorial #1: Navigating the directory tree. ![]()
0 Comments
Leave a Reply. |