# SHE analysis

**URL:** <https://forum.mothur.org/t/she-analysis/1821>\
**Category:** Theory behind mothur\
**Created:** [May 2, 2014, 10:24am UTC](https://forum.mothur.org/t/she-analysis/1821 "2014-05-02T10:24:45Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Andre](https://avatars.discourse-cdn.com/v4/letter/a/6de8d8/32.png) [@Andre](https://forum.mothur.org/u/Andre)\
**Post date:** [May 2, 2014, 10:24am UTC](https://forum.mothur.org/t/she-analysis/1821/1 "2014-05-02T10:24:45Z")

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I am currently working with biofilms obtained from a brevery enviroment. When analyzing my data with the collect.single or rarefaction.single command i observed an constant Shannon-Index even at a small sample size with low evenness values. So far nothing to be worry about. Next i was curious about the proportion of richness and evenness on the Shannon-Index at the different sample sizes. Itried to use the SHE analysis method based on Buzas and Hayek which uses the formula:

H(Shannon)= lnE + lnS

I compared the sum of the lnE- and lnS-values with the Shannon-Index obtained by mothur and found that they differ. For example i obtained 48 OTU´s and E=0,3361. The Shannon-Index calculated by mothur is 1,3301 but my calculation with the formula above is 2,78. Do you have any experience with this?

Thanks in advance

Andre

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**Author:** ![pschloss](https://yyz2.discourse-cdn.com/flex036/user_avatar/forum.mothur.org/pschloss/32/4_2.png) [@pschloss](https://forum.mothur.org/u/pschloss)\
**Post date:** [May 2, 2014, 11:12am UTC](https://forum.mothur.org/t/she-analysis/1821/2 "2014-05-02T11:12:47Z")

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Using the shannon index, evenness is calculated as shannon/ln(S). I’m not familiar with “SHE analysis” and my rules of logarithms are a bit rusty, but I don’t know how you get from E=H/ln(S) to H=ln(E) + ln(S)

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**Author:** ![Andre](https://avatars.discourse-cdn.com/v4/letter/a/6de8d8/32.png) [@Andre](https://forum.mothur.org/u/Andre)\
**Post date:** [May 2, 2014, 2:25pm UTC](https://forum.mothur.org/t/she-analysis/1821/3 "2014-05-02T14:25:00Z")

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My fault…

This formula just works if you are analyzing a given community, e.g watching the changes for a given set of species. If new species steadily approach the formula make now sense (as you assumed).

By the way, thank you for providing the mothur-software and for the support.

Have a nice weekend.

Andre