Figureing out N's


I'm measuring the physiological distance that certain axons retract after injury across different injury interval groups. I have approx 5 animals per injury interval, and approximately 100 measurements per animal

Should the N that I use for my ANOVA be 5 for each group or 500. meaning should I use all of the measurments seperately as my raw data, or should I get the mean of each animal and then plug those mean values for my raw data when doing the ANOVA?
Welcome gseif,

It seems that the overall sample size is 100*5*the number of injury interval groups. As described, it is a randomized block design with injury as the between factor and animal as the block. 100 measurements is quite a large number, are you applying any treatment to the different injury groups?
Thank you quark.

Actually, the injury is the same across all goups. No treatment is given. the only difference between the groups is the length of time of the injury.

5 groups are as such.

1: 1 week injury interval
2: 2 week injury
3: 4 weeK injury
4: 8 week injury
5: 16 week injury

I'm trying to quantify the degeneration that occurs after progressively longer injury intervals.

thanks, I really appreciate any advice that you can give
Last edited:
You are welcome gseif. If you have five injury group then total N=100*5*5=2500. I think the experiment is a randomized block design with injury time as the between factor and animal as the block. There are five blocks in each group, and 100 repetitions for each block.