Final answer:
The standard deviation of MAC measures variability. To prevent movement in 95% of patients, the minimum MAC required is around 1.96 standard deviations above the mean.
Step-by-step explanation:
The standard deviation of MAC (Mean Arterial Pressure) measures the variability or dispersion of the MAC values in a data set.
To prevent movement in 95% of patients, the minimum MAC required would generally be around 1.96 standard deviations above the mean, assuming a normal distribution. This is because 95% of the data falls within 1.96 standard deviations of the mean in a bell-shaped distribution.
In the context of amnesia alone, further information is needed to determine the required MAC.