# Errata

• The equations relation cross-correlation coefficient to signal-to-noise ratio on slide 7 of the PEET Fourier Shell Correlation presentation are incorrect. The correct relations are:
$SNR = \frac\left\{\right\}\left\{\right\} = \frac\left\{CCC^2\right\}\left\{\left(1 - CCC^2\right)\right\}$
and$CCC^2 = \frac\left\{SNR\right\}\left\{\left(1 + SNR\right)\right\}$
Signal-to-noise ratio is expressed here as a ratio of energies. Use the square root of this expression if the ratio of root-mean-square amplitudes is desired.