inst/explore-anacapa-output/docs/alpha-div-anova.md

In gauravsk/ranacapa: Utility Functions and 'shiny' App for Simple Environmental DNA Visualizations and Analyses

Statistical tests of differences in diversity

A frequent question in ecology is whether different communities (or different types of communities) are statistically different from one another in terms of their diversity. For example, do soils from grasslands, forests, and shrubby communities all have equally diverse bacterial communities?

One basic way of asking this question is to perform an ANOVA test between the groups we are interested in. In its simplest form, an ANOVA asks whether the difference in diversity between groups is statistically significant. A statistically significant difference would be indicated by very small P-value in the table below. It's important to keep in mind that two communities can have entirely different species assemblages and yet have the same diversity (e.g. Community A holds Species 1, 2, and 3; Community B holds Species 4, 5, and 6-- so each community has a species richess of 3, and is thus these communities are not "different from" each other in this context.)

Notes:

• There are many assumptions of an ANOVA, and the dataset you are investigating may break some (or even many) of these assumptions. We encourage you not to over-interpret the results below.
• ANOVAs only work when each group is represented by a few samples- in other words, if your data set only has one sample from a grassland, one from a forest, and two from a shrubland, it is impossible to statistically tease apart the differences among these groups. You will see NAs in the table below if this is the case.

These are the results from an ANOVA comparing diversity among groups in the variable you chose:

gauravsk/ranacapa documentation built on June 7, 2019, 4:03 a.m.