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. Author manuscript; available in PMC: 2022 Nov 14.
Published in final edited form as: Neuroimage. 2020 Jun 30;220:117112. doi: 10.1016/j.neuroimage.2020.117112

Table 1.

List of confounding factors tested.

Confounding factor Model (nlme syntax) Correlation of GABA+ and Glx residuals (corrected p-value) Significantly different from Vendor and Site
-: not significant
*: significant
Vendor and Site ~ Vendor + 1|Site r218 = 0.400, p = 3.38e-08 N/A
Demographics ~ Vendor*Age*Sex + 1|Site r218 = 0.384, p = 8.28e-08 –
Frequency drift ~ Vendor*Frequency Drift + 1|Site r218 = 0.377, p = 1.404e-07 –
Linewidth NAA ~ Vendor*Linewidth NAA + 1|Site r218 = 0.3967, p = 3.38e-08 –
Linewidth Water ~ Vendor*Linewidth Water + 1|Site r218 = 0.327, p = 1.0478e-06 –
Water area ~ Vendor*Water Area +1|Site r218 = 0.385, p = 8.28e-08 –
Concentration Cr ~ Vendor*Cr + 1|Site r218 = 0.163, p = 0.01625 *
Concentration NAA ~ Vendor*NAA + 1|Site r218 = 0.090, p = 0.184 *
Concentration Cho ~ Vendor*Cho + 1|Site r218 = 0.330, p = 9.312875e-07 –

Cr Creatine level; NAA N-acetylaspartate level; Cho Choline level.