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Questions tagged [diversity]

measures of diversity (or uniformity or inequality) such as: biodiversity in ecology, income inequality in economic. Examples are entropy and simpson's indices.

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17 views

Shannon Index normalization with S distinct species per site

Given S different species and M sites . Where in every site species are unique (not repeated within the site,that is there are no 2 individuals from the same species in the same site , but can be ...
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5 views

In VEGAN ADONIS, what does "method='bray' do when I pass in a distance matrix I already have (UNIFRAC)?

Suppose I have a distance matrix created by applying the weighted unifrac measure. For instance, using a phyloseq object: ...
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2answers
67 views

Testing when the profile of a sample has changed - degrees of freedom?

I've been messing around with the Shannon index for diversity $ H' = -\sum_i^R {p_i \ln{p_i}} $, and it's associated 'evenness' measure $E = H'/H_{\text{max}}$. I'm trying to come up with a way of ...
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8 views

Organising species and traits datasets correctly for fdisp function using the FD package in R

I am trying to compute some functional diversity metrics for three different species communities across three different sites, using the fdisp function in the FD package. I keep getting an error ...
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1answer
51 views

R: Statistically testing NMDS community differences

Situation I am comparing species communities at 6 different sites. Communities at each site were measured repeatedly over 5 years. I used NMDS plots, based on bray-curtis distance matrices using ...
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13 views

Comparing relative distances between separate ordinations

I have four sites: Treatment_1 and Control_1 of experiment 1 (8 plots in total) Treatment_2 & Control_2 of experiment 2 (8 plots in total) I ran an RDA for each experiment separately to compare ...
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1answer
48 views

Should I use Structural Equation Models (SEM) for my Functional Diversity (FD) study? (ECOLOGY RELATED)

I'm trying to calculate various functional diversity measures (Fric, Feve and Fdiv) for bird communities by using count data which is collected annually. My ultimate aim is to compare functional ...
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1answer
454 views

How to measure diversity (dispersion) of a categorical variable?

I have unemployment rates for 3 regions (North, Center, South). The unemployment rate is defined by (number of unemployed ($u$)/ active population ($pa$)). The unemployment rate by region ($r$) is $\...
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1answer
69 views

(Social) inequality measure based on chi-square

Is there any social inequality measure for categorical or ordinal variables, based on a goodness of fit chi squared test (distance from an uniform distribution)? ...
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0answers
72 views

Post hoc analysis survival data and maximum lifespan survival correction

I every body! Before to present my problem I apologize that I creates the same topic on the forum stackoverflow, but I think the best place for my question was here. I'm a PhD student and I'm ...
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0answers
31 views

Computing within-group diversity index in R

I am working with a df that has race and sex demographic variables. There is also a grouping variable indicating the work unit each individual observation belongs to. i.e., I want to compute a ...
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0answers
294 views

Can you use bray-curtis distances to evaluate standardized abundances in an NMDS?

So I'm trying to run an NMDS (using the vegan package in R) for a species X site matrix. Unfortunately the abundances of species are not inherently equal (If you can use that word) meaning that not ...
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0answers
147 views

Confusion about Pareto Principle and Pareto distribution

The Pareto principle, applied to wealth for example, says that around 20% of the population holds 80% of the wealth. Accordingly, it is said that a person's wealth follows a Pareto distribution. I'm ...
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1answer
66 views

Measuring how well data is evenly dispersed

I am trying to measure how well scores from members of a group are dispersed over possible values. Think of it as a measure of diversity function. Thus, ...
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1answer
125 views

Defining Diversity in Ensemble Learning

I have a few questions regarding on how diversity is defined since I've seen differing definitions in different papers. In the paper "Measures of Diversity in Classifier Ensembles and their ...
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1answer
147 views

Why does the Shannon index take the log of number and then multiply the number by that log?

I am looking to Shannon index formula in diversity. Part of the formula I am having trouble following. For example, 50 foxes at site 1, 60 foxes site 2 and 100 foxes site 3. Across all sites there ...
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48 views

how do I calculate overyielding in ecological temporal stability

I am investigating diversity-stability relationships and I am trying to test for the portfolio effect and insurance effect with my data. I understand that overyielding indicates the portfolio effect ...
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0answers
25 views

Analysing count data for biodiversity

So I'm confused about how to analyze some data for a biodiversity survey I'm undertaking. Incidences of birds are recorded at 25 stations on four sites (so 100 points in total). My response variable ...
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1answer
18 views

Average correlation as a criterion for choosing among indices

I am modelling industrial diversity in American MSAs (Metropolitan Statistical Areas) as an inverse Hirschman-Herfindahl index (IHH). I have a choice between 4 levels of NAICS industrial ...
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0answers
47 views

Comparing biological diversity before and after

I've got counts of two species in two treatments at two timepoints. I've got six replicates of each treatment. I'd like to know how to compare treatment diversity. As it is, I've calculated the ...
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61 views

Calculating average gender diversity at companies of various sizes

We have a dataset that lists employers in a fairly unique industry, the number of employees they have and the breakdown of employees as male or female. The size range of the companies in this ...
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3answers
698 views

Understanding the output of a fixed-effects-model in R

I am researching whether female representation changes the innovation output of companies. I have panel data of 30 companies over 10 years and "diversity, sales, r&dbudget, #employees" as my ...
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1answer
295 views

Calculation of the Shannon Index plotwise or over the entire population

Imagine I inventarized a forest with 28 plots. Do I calculate the Shannon-Index for each plot and take the average, or should I calculate the Shannon-Index over the whole population? I use R and the ...
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1answer
217 views

What is statistical diversity and how is it measured? (dataset with properties of materials)

I'm curious how one would define and measure statistical diversity for a research project of mine. My motivation is to understand the statistical space of materials. Each material has a set of ...
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1answer
138 views

Statistical test for comparing species diversity based on frequency at two points

I am trying to quantify similarity between these two locations taking into account species frequency: Chicago   Blue Jay: 0.79   American Crow: 0.25   Blackpoll ...
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0answers
832 views

Small sample size - repeated measure ANOVA or something more simple?

I have data from an ecological study on wasp abundance and diversity across a forest which I am trying to analyse appropriately. We have abundance data from ten locations that were sampled twice, ...
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0answers
112 views

How to combine two variances of Simpson's diversity index?

I know how to combine two common variances with mean and sample size. However, I don't know how to combine two variances if a variance has a special form. From Simpson's diversity index, he proposed a ...
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0answers
78 views

Understanding / plotting 2 variables where both are allowed to vary in logistic regression

I'm hoping someone can help clarify a few things for me. I ran some relatively simple logistic regressions in r and am having trouble with interpretation. I'm interested in the effects of elevation ...
4
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1answer
495 views

Standard error for Shannon's index in R

I am interested in examining how the species diversity of bird communities change following timber harvest and have used Vegan in R to run my analyses. Below is a sample of my count data. Plot names ...
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1answer
1k views

Weighted entropy as a measure of diversity

Suppose that you are a company manager and you are looking for a statistical measure that defines the international reputation of your company. So, you collect data on your clients and the countries ...
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0answers
113 views

How to analyze the determinants of various inequality indexes over time?

I have data concerning the distribution of income, at the individual level, i.e. I have for each individual income and some socio-demographic descriptors. I have this kind of data for several years, ...
6
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4answers
9k views

Observational vs quasi-experimental design?

I am having some difficulty understanding the difference between and identifying an observational vs quasi-experimental design. From my understanding, an observational study is one in which the ...
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1answer
150 views

What's the most adequate test/tests for this study?

I'm a PhD student (Biodiversity and Animal Ecology). I am preparing a scientific article to submit and I need help in statistical analysis of my data. In this message I will try to provide as much as ...
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1answer
121 views

Vectors for biodiversity indices in RDA plot

I'm doing partial distance based (db-)RDA analysis of nematode community data. I have got the triplots already. They contain vectors of environmental data. Is it possible to overlay a second set of ...
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1answer
181 views

Comparing Species diversity of 32 plots between years

I need to know what type of test to use to compare species diversity between 2 years. I have been analyzing a species survey data set collected in 2012 and 2014. The data include stem count (...
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2answers
3k views

Biased bootstrap: is it okay to center the CI around the observed statistic?

This is similar to Bootstrap: estimate is outside of confidence interval I have some data that represents counts of genotypes in a population. I want to estimate genetic diversity using Shannon's ...
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4answers
8k views

Statistical test to perform on species diversity / Simpson's diversity index

I have a set of data from each of the two sites I am measuring for plant species diversity. I plan on using the Simpson's diversity index (SDI), which combines species richness (number of different ...
3
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1answer
1k views

Calculating Diversity using normalized species counts

I am trying to calculate the change in diversity of species encountered throughout time. My dataset is comprised to detections of tagged fish for 48 consecutive weeks. My thought was to bin the ...
2
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0answers
61 views

Quantifying tree height diversity or heterogeneity

I am analyzing data collected in the field for a habitat selection study of a large mammal. I have ~1300 plots that were sampled. I am trying to find a good way to quantify the diversity of tree ...
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1answer
73 views

Statistical measure of international diversity

I've got a large collection of geotagged tweets, each linking to an article from a given author. For each author, I'd like to derive a number that describes how diverse is their list of tweeting ...
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2answers
478 views

How to express “inequality” of a distribution in one number?

I've got an educational game in the work that challenges players to redraw U.S. state borders in a way that reduce the inequality between big-population and small-population states. As they play, they ...
2
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2answers
532 views

Derivation of the Simpson index

I'm interested in the derivation of the Simpson diversity index. I found the normal interpretation of this index, but I'm not able to see what's the "mathematical background" of the formula. I read ...
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3answers
784 views

How would re-weighting American Community Survey diversity data affect its margins of error?

Background: My organization currently compares its workforce diversity statistics (ex. % persons with disabilities, % women, % veterans) to the total labor force availability for those groups based on ...
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1answer
53 views

Calculating linguistic diversity of a text with respect to size

I'm doing linguistics work and I'm trying to make a measure of linguistic diversity in a text. A simple calculation seems to be linguistic uniformity ( or diversity) = number of words / unique words ...
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2answers
2k views

Comparison of two Simpson indices using t-test

I would like to compare two Simpson Indices from two different populations. I have calculated their variance, as it is done in the original paper by Simpson regarding measures of diversity and I have ...
5
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1answer
401 views

Measure of dispersion over unordered set

I'm looking for a measure of dispersion, such as standard deviation, that can be used when distributing to an unordered set. Specifically: A bucket distribution assigns a non-negative value to each ...
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0answers
370 views

Mixed repeated measures Anova

I'm trying to assess the influence of fertilisation and irrigation on biodiversity in a complete randomized block design. I have two treatments, one control and two blocks. Treatments went on for ...
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1answer
5k views

What test should I use with shannon diversity index values?

What sort of test should I use to get the p-value after getting a shannon diversity index? Also does anyone know if and how they can be done using PRIMER 5?
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1answer
211 views

Basic descriptive statistics on an irregular data set

I have not used my stats in a while and was interested in how the group would handle the following: I have a multi-year insect data set that has irregularities in trapping effort, trap type and area ...
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1answer
211 views

Help with creating a formula for “diversity coefficient”

I am creating a small webapp and a part of it is generating a number (I like to call it diversity coefficient) that would represent how "diverse" someones listening habits are. The problem is - I am ...