# Testing significance of difference between two averages.

• Jan 10th 2011, 05:51 PM
OSNS
Testing significance of difference between two averages.
Hi all,

Firstly, I apologise if this is in the wrong section of the forum but I know absolutely nothing about math.

I've been asked to find several values between two mean velocities and figure out if the means are "significantly different":
1. P value
2. t value
3. t crit value
4. df

Mean velocity A: 0.471m³/s
Mean velocity B: 0.205m³/s

(These are the means of two data sets on Excel with 40 samples in each)

If anybody could shed some light as to what these are and how to calculate them, as simplified as possible, I'd be extremely grateful.

OSNS
• Jan 10th 2011, 05:55 PM
dwsmith
An arithmetic mean is calculated by adding up the 40 observations and than dividing by the number which is 40.

$\displaystyle \displaystyle\frac{1}{n}\sum_{i=1}^{40}x_i$
• Jan 10th 2011, 06:42 PM
pickslides
Quote:

Originally Posted by OSNS
I've been asked to find several values between two mean velocities and figure out if the means are "significantly different":
1. P value
2. t value
3. t crit value
4. df

Mean velocity A: 0.471m³/s
Mean velocity B: 0.205m³/s

(These are the means of two data sets on Excel with 40 samples in each)

Have you seen the t-test for difference in means?

Excel has a data analysis tool that can perform this test.

More reading: Testing Differences Between Means