Metal accumulation dependence on weight and pollution


New Member
I'm working on metal accumulation in two landsnail species and it includes their kidneys and feet. I have concentrations of 7 metals in these organs and I need to check, if accumulation depends on weight. I tried to categorise snails into 3 weight groups within species, then I took a sum of conc. of metals in each snail (conc. of all metals in kidney + conc. of all metals in foot) and used Kruskal - wallis test. I don't know if it is correct and how to check dependence of every metal separately.
Also, I need to check, if metal accumulation in snails depends on pollution of the site. There will be 3 pollution categories, too. Which tests and how should I use?
I am using Statistica 10 and GraphPad prism 7 programs.
Hi, as far as I see you have a continuous outcome-variable (for each metal type the concetration) and as predictors you have (1) organ (categorical: kidney / feet) (2) species (categorical), (3) weight (continuous), and (4) pollution (categorical). What you can do is an ANCOVA for each metal type. Kruskal-Wallis is also OK, but you probably loose sharpness by converting continuous variables to categorical ones...