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.
Population Standard Deviation Example: To find the Population Standard deviation of 1,2,3,4,5. Perform the steps 1 and 2 as seen in above example. Step 3: Now find the population standard deviation using the formula. â10/â5 = 1.414 . Variance Example: To find the Variance of 1,2,3,4,5. After finding the standard deviation square the values. (1.58113) 2 = 2.4999 Same for Population standard deviation