An ecologist investigated the relationship between the concentration of a heavy metal pollutant in soil (measured in mg kg−1\text{mg kg}^{-1}mg kg−1) and the mean root length of Taraxacum officinale (measured in mm\text{mm}mm) across 15 distinct industrial sites.
The ecologist wants to determine whether there is a significant correlation between soil heavy metal concentration and root length.
Which statistical test is most appropriate for this analysis?
Student's ttt-test
Chi-squared (χ2\chi^2χ2) test
Spearman's rank correlation coefficient
Standard error of the mean
