# Thread: Have I calculated the sensitivity coefficient correctly here?

1. ## Have I calculated the sensitivity coefficient correctly here?

I have the following formula from my text book:

https://i.imgur.com/BZZkRzL.jpg

So for my example, I have the following:

Base value input: 110
Increased input by 10%: 121

Output before the 10% increase: 520
Output after the 10% increase: 578

So when calculating the sensitivity coefficient as mentioned in my text book, is this correct?

$S_x=\frac{(578-520)/520}{(121-110)/110}$

Basically, what I'm confused about are the denominators in the fraction. The "input" and "output" that you have to divide by. Am I supposed to use the values before the sensitivity analysis like I've done? Or should I use the values after the sensitivity analysis instead (so dividing the difference with 578 for output and 121 for input)?

Thank you!!

2. ## Re: Have I calculated the sensitivity coefficient correctly here?

Yes, you divide by the initial values, x and y, not the changed values, $x+ \partial x$ and $y+ \partial y$.