Statistical tests can be classified into 5 types, based on the measurement scales of your response and explanatory variables. Are those scales continuous, or grouped?

Response variable

- the variable you are trying to understand
- usually plotted on the Y axis
- continuous (1.4, 2.5, ...) or grouped (above vs. below detection limit)

Explanatory variables

- variables used to explain Y
- usually plotted on the X axis
- continuous (1.4, 2.5, ...) or grouped (ag, urban, forest)

Choose (click on) your procedure based on whether your variables are continuous or grouped:

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Continuous Y Grouped X

Compare differences among two or more groups

Continuous Y Continuous X

Relate a continuous Y variable to one or more continuous explanatory variables.

Continuous Y both Grouped and Continuous X

Is there 1 or more than 1 regression line?

Grouped Y Grouped X

Do percentages of Y categories (detect / nondetect) change between two or more groups (June vs. Sept)?

Grouped Y Continuous X

Do percentages (% hits) change as one or more explanatory variables (thickness) change?