vignettes/articles/paper_beta.md

In smasongarrison/discord: Functions for Discordant Kinship Modeling

title: 'discord: Functions for Discordant Kinship Modeling' tags: - kinship modeling - behavior genetics - causal inference authors: - name: Jonathan D. Trattner orcid: 0000-0003-0872-7098 affiliation: 1 - name: S. Mason Garrison^[Correspondence should be addressed to [e-mail]] affiliation: 1 affiliations: - name: Wake Forest University, Winston-Salem, NC index: 1 date: 21 October 2020 bibliography: paper.bib editor_options: markdown: wrap: 72

Summary

Behavior genetics involves examining the genetic and environmental sources peoples' behavior. Specifically, it leverages genetic and environmental differences to better understand individual variation. Classic methods focus upon description, often by comparing different kinds of twins. However, behavior genetics can do so much more than merely compare twins. It can be used to evaluate causal claims using any kind of kinship groups, cousins, siblings, etc. In this package, we provide a series of tools to harness the power of behavior genetics, using publicly available data.

Although randomized studies on identical twins are the gold standard to determine causality, they are not always feasible due to small sample sizes and high costs. As an alternative, our team has developed a quasi-experimental paradigm (Garrison & Rodgers, 2016) that allows us to control for gene-and-environmental variance among kinship pairs (siblings, cousins, etc.) and shed light on causal relationships arising from the "nature vs. nurture" debate. The crux of this paradigm relies on the discordant-kinship model, which in turn requires specifically structured data. In addition, given the growing interest in limiting underpowered studies, we also include simulation functions so that researcher can create custom simulated data.

Statement of need

discord is an R package that provides functions for discordant kinship modeling and other sibling-based quasi-experimental designs. It has highly customizable, efficient code for generating genetically-informed simulations and provides user-friendly functions to perform discordant-kinship regressions. It integrates seamlessly with the NlsyLinks R package, which provides kinship links for the National Longitudinal Survey of Youth -- a cross-generational, nationally representative survey of over 30,000 participants for up to 35 years [@beasley_nlsylinks_2016]. It has been used in previous publications (cite, Mason, cite!) and supports the principles of tidy data [@wickham2014] utilizing the broom package [@robinson2020] to report model coefficients.

Mathematics

The core of the discordant kinship model can be explained with a simplistic case where a behavioral outcome $Y$ is predicted by one variable $X$, the discord regression model relates the difference in that outcome, $Y_{i\Delta}$, for a given kinship pair, indexed as $i$, in the following model, where $X_{i\Delta}$ is the difference in the predictor.

$\mathrm{Y_{i\Delta}} = \beta_{0} + \beta_{1}\mathrm{\bar{Y_{i}}} + \beta_{2}\mathrm{\bar{X_{i}}} + \beta_{3}\mathrm{X_{i\Delta}}$

where,

$\mathrm{Y_{i\Delta}} = \mathrm{Y_{i,1}} - \mathrm{Y_{i,2}}$

$\mathrm{X_{i\Delta}} = \mathrm{X_{i,1}} - \mathrm{X_{i,2}}$

and $1$ and $2$ identify the individuals within the kinship pair, defined by

$\mathrm{Y_{i,1}} > \mathrm{Y_{i,2}}$

$\mathrm{X_{i,1}} > \mathrm{X_{i,2}}$

Citations

Acknowledgements

We acknowledge contributions from Cermet Ream, Joe Rodgers, and support from Lucy D'Agostino McGowan on this project.

References

smasongarrison/discord documentation built on March 4, 2024, 12:55 p.m.