Category Archives: Statistics

Proper Consideration of Error Propagation in Data Analysis

This post is motivated by working with my lab mate Elizabeth Guinessey on some data analyses for her thesis. The goal of the study is to investigate how greenhouse gas flux rates differ in various vegetation types in salt marshes. To do … Continue reading

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A Follow Up on Plotting Everything Against Everything Else

I wrote a blog post on the practice of plotting everything on everything else in ecology a while ago. Since writing the post, I have had quite a few insightful conversations with colleagues and did some readings on this issue. … Continue reading

Posted in Academic skills, Statistics | 2 Comments

T Test without Normality Assumption

We are teaching t test and ANOVA this week in the introductory ecology lab. As I prepare the teaching materials, one thing about t test caught my attention. In many statistics classes, I was taught that the variables under comparison … Continue reading

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Guest Blog: Collaborative Research in Odum School of Ecology

Note from Chao: John and I investigated the research focus and collaboration of faculties at Odum School of Ecology. I posted the analyses on the diverse research areas a few days ago. John has graciously agreed to analyze the collaboration … Continue reading

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Diverse Research Areas in Odum School of Ecology

John Vinson and I had an interesting conversation on how to visualize the collaboration and research focus among labs on our drive back from Atlanta. One idea is to classify labs based on similarity in research focus. We can look at … Continue reading

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The Practice of Plotting Everything Against Everything Else

I have seen the following scenario a lot in ecological research. After we collected bunch of data from field, we often explore the data first. We plot response variables of interests against all the possible predictors we measured. Some may show a … Continue reading

Posted in Academic skills, Statistics | 4 Comments

Dealing with Overdispersion in Generalized Linear Models

I talked with my fellow graduate student Rachel Smith this morning on analyzing her species abundance data. The goal is to use environmental variables to predict the abundance of species. One particular concern she has is overdispersion. That is, the … Continue reading

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Why Is R2 Not a Measure of Association Strength?

One of the most common mistakes I saw when teaching simple statistics in introductory ecology lab is a misinterpretation of R2 from a linear regression. Students tend to use R2 as a measure of association strength. That is, a high … Continue reading

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A Complete Work Flow of Fitting a Simple Linear Model

I recently discussed with one of my fellow graduate students testing linear contrasts from a two way ANOVA model. He was a little confused about implementing it in R and interpreting some of the model outputs. As I discussed in an earlier … Continue reading

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The Ideal Introductory Statistics Course for Ecologists

There has been a lot of discussions on offering an introductory statistics course as part of the graduate students’ curriculum at Odum School of Ecology over the years. A few different kinds of introductory statistics courses were offered in recent … Continue reading

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