N1m amplitude as a function of N-acetylaspartate. Linear regression plot of the amplitude of the first N1m vs. N-acetylaspartate (NAA) (R
2 = 0.369, F(1,13), p = 0.016). The 95% confidence intervals are represented by dashed lines. The insert shows the normal probability plot of the residuals, indicating that the errors are normally distributed. IU, institutional unit.