In the U.S., doctors usually get suspicious when a PSA level is 4.0 ng/mL. But studies show that many men with levels well above 4.0 ng/mL do not have cancer. And many men with prostate cancer have PSA scores well below this level. There are a lot of ways to tweak the PSA test to try to get better results.
The Standard Deviation Formula. In this formula, x is the value of the mean, N is the sample size, and x i represents each data value from i=1 to i=N.. The â symbol indicates that you must add up the sum. (x 1 - x) 2 + (x 2 - x) 2 + (x 3 - x) 2 + (x 4 - x) 2 + (x 5 - x) 2. . . + (x N-x) 2.
Standard Deviation Calculator. The following is a free online tool to calculate the standard deviation, variance, mean, sum, and confidence range for given numbers. The value used to calculate the confidence range is the sample standard deviation value.tandard Deviation. The following is the definition of the standard definition Ï, also called population standard deviation if the entire population can be measured, where Âµ is the expectation, x i is one sample value, and N is the total number of samples. Ï 2 is called variance.