I’m currently in ecology working on statistics. So far all I know is that a parametric test is used for frequency polygon with a bell shape that has continuous variables and that a non parametric is used when data shows a skewed distribution with discrete variables. Is that all? I don’t need to know it in detail just more detail to answer “what is the difference between a parametric and nonparametric test? Thanks.
In: Mathematics
A parametric test makes assumptions about the underlying distribution of the data whereas a non-parametric test does not.
For example, a t-test assumes that error terms are distributed normally with a homogeneous variance along the distribution.
A Spearman Rank Correlation test doesn’t care about how the underlying data is shaped. It just asks about the correlation in the ranks of associated data points.
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