Microbiome AB/BA Crossover Design

The motivation for this post was also recent question on twitter asking how one might approach the analysis of an AB/BA crossover study when the goal is to estimate the difference in the relative abundance of microbial taxa under treatments A and B.

Sample Size Considerations for Microbial Metagenomics Research

One of the most common questions we get from investigators at the Microbial Metagenomics Analysis Center (MMAC) is how many samples should I collect for my study? Even once we have a clearly stated and testable hypothesis, this is not always easy, since sample size calculations for microbiome studies are typically not amenable to closed form solutions (i.

ANCOVA for Analyzing Pre-Post Microbiome Studies

I recently analyzed some data from an experiment with a pre-post study design where our estimands of interest were the baseline adjusted mean difference in Shannon diversity and species differential abundance between arms at post-treatment.

Examining Coverage of CLR Regression

I was thinking recently about the performance of linear models for differential abundance testing in microbiome studies (see here for an example) despite the sparse, extremely non-normal, and compositional nature of mixed microbial community taxonomic profiles.

Reproducibility and intermethod reliability of a calcium food frequency questionnaire for use in Hispanic, non-Hispanic Black, and non-Hispanic White youth

BACKGROUND: A dietary assessment instrument designed for use in a nationally representative pediatric population was required to examine associations between calcium intake and bone mineral accrual in a large, multicenter study. OBJECTIVE: To …

Within- and between-individual variation in nutrient intake in children and adolescents

BACKGROUND: Little is known regarding the number of 24-hour recalls required to rank-order children and adolescents on usual intake for diet-disease studies. OBJECTIVE: To determine the within- to between-individual variance ratios and number of …