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I'm having a problem with choosing between Pearson and Spearman correlation. I'd like to understand clearly why I should use one or the other. I have read the questions already asked here about this subject, but I am still confused, plsease if someone can help:
The kind of data I'll correlate: I will have an abundance index (of mushrooms) that I'll correlate (test the relationship) with some environmental and biogeographical data, such as: altitude, plant species, soil PH, etc. The aim of doing this is to find positive or negative relationships, to explore if these factors determine the distribution of the mushrooms, and explain how they do this.
I dont know if I should the " Answer option" here, I'm not familiar with the use of the "forum"?. Thank you all for your valuable information and details, I have clearer idea now!
According to the answers if I have ranks so Spearman is most suitable. For plants species, I'll use also an abundance index which i'll correlate with the abundance index of mushrooms. For the other factors(variables) I'll use numerical data PH will vary between (0 and 14), for altitude there will me also " numbers in meter". For some other varibales I might have " ranks" ! so I can use Spearman as it will explore the relationships whatever these are?