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.
The stabilator is another way (Piper). It is an airfoil that in one piece acts as both stabilizer and elevator. The trim control of the stabilator acts as both a trim and anti-servo tab (power assist). The yoke applies control forces to the tab to move the entire control. No change in trim technique is required in either case. Ideally an aircraft would have a three-axis trim; elevator, rudder, and aileron.