Obtaining Average Stress & Strain From Load Vs Deflection

Hello All

I was hoping someone could help me with my understanding of obtaining Stress & Stress From load deflection data.

I have a timber sample which underwent a compression test (dimensions of 30 x 30 x 30).

The test was done 3 times in order to obtain an average.

1) One the first test I had 100 rows of load vs deflection data, on the second test I had 112 rows of load vs deflection data and the 3rd test I had 96 rows. I was wondering if someone could tell me how i would obtain an average of the Load vs Deflection and an Average Stress and Strain???

2) The question relates to Strain which I know is obtained from Change in Length / Original Length - My question is if I had the data below and given the fact that the dimension of my sample was 30 x 30 x 30 then would the following values of strain be correct:-

Load, Deflection, Strain
2, 2100, 2/30 = 0.0667
2.5, 2300, 2.5/ 30 = 0.083

Any help or guidance would be greatly appreciated.

I have attached a screen shot of my data of all three tests.

Thank you.[ATTACH=CONFIG]2514[/ATTACH]