TY - JOUR
T1 - False positive rates in Voxel-based Morphometry studies of the human brain
T2 - Should we be worried?
AU - Scarpazza, Cristina
AU - Tognin, Stefania
AU - Frisciata, Silvia
AU - Sartori, Giuseppe
AU - Mechelli, Andrea
PY - 2015/5/1
Y1 - 2015/5/1
N2 - Voxel-based Morphometry (VBM) is a widely used automated technique for the analysis of neuroanatomical images. Despite its popularity within the neuroimaging community, there are outstanding concerns about its potential susceptibility to false positive findings. Here we review the main methodological factors that are known to influence the results of VBM studies comparing two groups of subjects. We then use two large, open-access data sets to empirically estimate false positive rates and how these depend on sample size, degree of smoothing and modulation. Our review and investigation provide three main results: (i) when groups of equal size are compared false positive rate is not higher than expected, i.e. about 5%; (ii) the sample size, degree of smoothing and modulation do not appear to influence false positive rate; (iii) when they exist, false positive findings are randomly distributed across the brain. These results provide reassurance that VBM studies comparing groups are not vulnerable to the higher than expected false positive rates that are evident in single case VBM.
AB - Voxel-based Morphometry (VBM) is a widely used automated technique for the analysis of neuroanatomical images. Despite its popularity within the neuroimaging community, there are outstanding concerns about its potential susceptibility to false positive findings. Here we review the main methodological factors that are known to influence the results of VBM studies comparing two groups of subjects. We then use two large, open-access data sets to empirically estimate false positive rates and how these depend on sample size, degree of smoothing and modulation. Our review and investigation provide three main results: (i) when groups of equal size are compared false positive rate is not higher than expected, i.e. about 5%; (ii) the sample size, degree of smoothing and modulation do not appear to influence false positive rate; (iii) when they exist, false positive findings are randomly distributed across the brain. These results provide reassurance that VBM studies comparing groups are not vulnerable to the higher than expected false positive rates that are evident in single case VBM.
KW - Balanced design
KW - False positive rate
KW - Neuroimaging
KW - Unbalanced design
KW - Voxel-based Morphometry
UR - http://www.scopus.com/inward/record.url?scp=84924940709&partnerID=8YFLogxK
U2 - 10.1016/j.neubiorev.2015.02.008
DO - 10.1016/j.neubiorev.2015.02.008
M3 - Article
AN - SCOPUS:84924940709
SN - 0149-7634
VL - 52
SP - 49
EP - 55
JO - Neuroscience and Biobehavioral Reviews
JF - Neuroscience and Biobehavioral Reviews
ER -