I'm in a class right now using SPSS, and am working on my final project. My hypthoses are basically: does nutrient/water quality/invasive species affect invasion rate? My data is longitudinal, recoded to start at year 0. I have variables for nutrients, other water quality parameters, and presence/absence of each invasive species. I am having trouble figuring out how to set up my data so it works in SPSS. I would like to do hierarchical regression, as that makes the most sense based on my literature review, but I have no idea how I should work it so it works longitudinally and with my 55 lakes. The only way I can think to set it up would be to split it into yearly based variables but that means I'll have way, way too many variables for any meaningful regression.
Example of dataset: (I'd attach the actual excel file but I keep getting errors)
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