I have data for the number of mice in an area of 13 years.
$\begin{bmatrix}
\text{Year} & \text{#mice} \\
1995 & 30 \\
1996 & 113 \\
1997 & 106 \\
1998 & 50 \\
1999 & 19 \\
2000 & 20 \\
2001 & 20 \\
2002 & 63 \\
2003 & 13 \\
2004 & 69 \\
2005 & 100 \\
2006 & 56 \\
2007 & 160 \\
\end{bmatrix}
$
I want to know the net percentage change over the 13 years.
I have done $\frac{160-30}{30}\cdot 100 = 81.25\text{%}$, is this correct, is just doesn't seem right to me as it doesn't take into account all the other values.
So I decided to add all the differences between each year, which = $130$, I summed the values, which = $819$. So I tried $\frac{130}{819} \cdot 100 = 15.87\text{%}$, which seems more reasonable, but is it mathematically correct?
Thanks in advance for any help!
Best Answer
Percentage change over all years.
$\frac{\text{Final Value - Initial Value}}{\text{Initial Value}} \times 100$
= $\frac{160 - 30}{30} \times 100$
This is correct method.
If you take account of all terms still you got 130. So its the right method i.e $+83-7-56-31+1+0+43-50+56+31-44+104 = 130$