I'm confused about how to arrange data for PCA & factor analysis. I want to see the association between physico-chemical variables and infection parameters of fish. In addition, I want to correlate with other features of fish.
You need grouping variable and independent variables for PCA and DFA analysis in SPSS. If you have 2 populations/species take grouping variable as name of the population/species then put the corresponding independent variables against the grouping variable. For example...for two populations..
Population Varible 1 Variable 2 variable 3 variable 4
1 1.846163372 2.750819762 1.066226848 3.570076888
1 1.319154501 1.783463268 0.751887394 2.849958907
1 2.437551691 3.997620437 1.395285115 4.326324655
1 1.636695363 1.936954755 2.428583519 2.94560643
1 1.624042034 2.164522791 0.904074934 3.13419123
1 1.66323773 2.455149511 0.975777635 2.922877598
1 1.657815735 2.343986283 0.987542906 3.034960038
1 2.078424222 2.548837677 1.060420278 2.795921084
2 1.846163372 2.750819762 1.066226848 3.570076888
2 1.319154501 1.783463268 0.751887394 2.849958907
2 2.437551691 3.997620437 1.395285115 4.326324655
2 1.636695363 1.936954755 2.428583519 2.94560643
2 1.624042034 2.164522791 0.904074934 3.13419123
2 1.66323773 2.455149511 0.975777635 2.922877598
2 1.657815735 2.343986283 0.987542906 3.034960038
2 2.078424222 2.548837677 1.060420278 2.795921084
For variables given above you can use your parameters like DO, Alkalinity, or Organism length, height etc...