I have two data sets, over a period of time that I would like to compare. I am very unfamiliar with statistics so sorry if this is simple. I need to use SPSS.
I am comparing the number of journal articles published relating to a two different disciplines, over a period of 40 or so years.
Is it possible to statistically compare these two 'lines' to give more argument to the trends?
Based on the data collected, the current trend is they are both very similar, and then in the last 10 years, one rises substantially, and the other begins to fall. Is there a way I can statistically infer a relationship between them, especially the part where one begings to rise and one begins to fall?
Do I need to standardise my data to account for the fact one of the lines has a smaller sample size? Edit: the sample sizes are taken over the same amount of years, but see below, one has considerably more hits than the other - would standardising make the relationship clearer?
I hope this makes sense.
Edit: this is how my data appears already. I'm not sure if anyone knows a better way of representing it, I know the large time frame makes it quite hard to see what is going on until the huge spike
What I would like to infer, if possible, that there may be a relationship between the green line substantially rising, and the black line starting to fall off