why is mean 0 and standard deviation always used? why does mean 0 and standard deviation always be used what is a mean 0 and standard deviation what means mean 0 and standard deviation why are mean 0 and standard deviation always used? what is mean 0 and standard deviation why are sd and mean always used in math why are the mean 0 standard deviation always used? what is mean and standard deviation why is the standard deviation of a z score flat what is the standard deviation of mean why do z scores always use standard deviation or mean when are mean 0 and standard deviation always used? why do standard deviations always use mean and standard deviation why is meant 0 and standard deviation always used why is standard deviation and mean 0 always used in statistics why is the standard deviation of a z score a flat distribution why does mean mean 0 mean p mean sd one what is the difference between mean 0 and standard deviation what is the normal distribution of sd1 in stats