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.
Percentage relative standard deviation is a widely used statistical tool but strangely there is no automated function in any version of Microsoft Excel. Relative Standard Deviation in Excel 2003, 2007 & 2010 %RSD is a powerful tool to statistically inspect the variation in sets of data but a specific function is not available in Excel 2003, 2007 or even 2010. To calculate the %RSD in Microsoft Excel a short formula must be used: = (STDEV(Data Range) / AVERAGE(Data Range))*100 = (STDEV(A1:A11) / AVERAGE(A1:A11))*100. The above %RSD example has been entered into the Excel formula bar and will calculate the percent relative standard deviation of the 5 value data set E6 to E11. In the cell where the formula is written a value between 0-100 will be reported.