Help with SPSS bachelor thesis

[Rache]

Hi everybody,

I got a little complicated question, but I'll try to make it as clear as possible.
For my thesis I am doing research on the impact of the shifts within GOLD classifications on the quality of life of COPD patients. The dependent variable is the quality of life and the independent variable is the GOLD classification.
I only look at the GOLD 2011 and the GOLD 2015 classification, with the GOLD classification as a categorical variable: GOLD A, B, C and D. One of my sub-questions I have difficulties with is: 'To what extent does the quality of life change in the GOLD 2011 and GOLD 2015 classificationgroups from baseline to year 1? I do not know exactly what tests I should run in order to find an answer to this question.
What I do know is that the knowledge about  the (level of) quality of life within the GOLD classification can be found by running a One Way Independent ANOVA test (if the dependent variable is normally distributed) or Kruskal-Wallis test (if the dependent variable is not normally distributed) with the GOLD 2011 (ABCD) and GOLD 2015 (A BC D).

My main research question is 'What is the relation between the quality of life of COPD patiënts and the different GOLD 2015 classificationgroups and in which extent does this differ from the GOLD 2011?

Thanks in advance!

 

[lewin]

Some great advice is to never design a study where you don't have a data analysis plan in advance. Since it's too late for that... 

Are these the same individuals at 2011 and 2015 and is it possible for someone's GOLD classification to change from 2011 to 2015? Because if so, the most appropriate analysis might be a multilevel model where GOLD predicts quality of life nested within individuals, and time is a repeated-measures factor. That's pretty complex stuff though.

If people stay the same GOLD classification across years, a mixed-model ANOVA with time (2011 vs. 2015) as a repeated measure and level (a,b,c,d) as a between subjects variable might work.