I think you might want to look into a repeated measures ANOVA, or you can possibly use regression and put in the time as a control variable. You may also be able to use robust standard errors for the ANOVA by applying a bootstrap to your data. The non-parametric anova is a kruskall-wallis. Not sure if you can do repeated measures on that in SPSS.

Andy Field's book (and the tons of hand outs he has on his website) will be really useful resources at this stage for more info on all the points I have made above. Take a bit of time and read it thoroughly and slowly as it is wordy but it really written for non stats people, just portion out time to read it - will make things less painful in the long run. The other book is the SPSS survival guide by Juile Pallant which is a bit less wordy - maybe start there and then read Field.

Good luck

Hi Ally, I don't use SPSS but thanks for the recommendations. The book I have is helpful (ANOVA how to choose and contruct models for the Life Sciences) I just need to decide exactly which parts are nested within which in my data - I have a 3x3 design with 3 sites of each 'type' in 3 areas. But the areas are close and my examiners say they aren't replicates as they interact. So I can work out how to nest the 3 sites into areas, just not how to account for the similarities in area....if that makes any sense at all aha. And that is all before I start working out the temporal analysis parts (the first chapter I'm working on doesn't have temporal repeats, two of them do though and they are next on my list!).

I'm feeling a bit more positive about understanding my stats, but getting frustrated at myself for how I saved my data, it's really hard to work out where I saved what...I'm sure it made perfect sense when I was working on it every day haha.

My niece is here this week though so will just be squeezing in an hour here and there of work as we have important sigh-seeing to do!