# Margin of Error

Discussion in 'Off Topic' started by Mark Laszczuk, 11th Jun, 2008.

1. ### Mark LaszczukWell-Known Member

Joined:
16th Aug, 2005
Posts:
793
Location:
Brisbane
I'm trying to work out a formula for calculating margin of error in Excel. Had a look around Google, but didn't find what I was looking for. What I need to do is determine the percentage difference between two numbers.

Let's say I project a dividend of 50 cents for a given year. However, the actual dividend is 45 cents. So the margin of error on this is about 10%, give or take (45 cents is 90% of 50 cents).

Does anyone have a formula I could pinch please?

Mark

2. ### Simon HampelCo-founderStaff Member

Joined:
9th Jun, 2005
Posts:
4,774
Location:
Sydney, Australia
"Margin of Error" has a specific statistical meaning and relates to sample sizes and error rates from survey data. I'm not sure if that's actually what you are looking for ?

If you just want to calculate the percentage difference between two numbers (predicted and actual), then surely this would do the trick:

A1 = prediction
A2 = actual

formula =(A2-A1)/A1

if the actual is less than the prediction, result will be negative. Result can be formatted as a percentage.

Is that what you want? Or are you after something more statistical?

3. ### Mark LaszczukWell-Known Member

Joined:
16th Aug, 2005
Posts:
793
Location:
Brisbane
Mate, that's exactly what I needed, thanks! I was racking my brains for about an hour last night trying to work out the formula for it. Maybe I shouldn't try so hard at 3 in the morning.

Mark