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Earlier this month, I taught at the Summer Research Training Institute on Single-Case Intervention Design and Analysis workshop, sponsored by the Institute of Education Sciences’ National Center for Special Education Research. While I was there, I shared a web-app for simulating data from a single-case design. This is a tool that I put together a couple of years ago as part of my ARPobservation R package, but haven’t ever really publicized or done anything formal with.

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I’m very happy to share a new paper, co-authored with my student Danny Swan, “A gradual effects model for single-case designs,” which is now available online at Multivariate Behavioral Research. You can access the published version at the journal website (click here for free access while supplies last) or the pre-print on PsyArxiv (always free!). Here’s the abstract and the supplementary materials. Danny wrote R functions for fitting the model, (available as part of the SingleCaseES package) as well as a slick web interface, if you prefer to point-and-click.

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Last night I attended a joint meetup between the Austin R User Group and R Ladies Austin, which was great fun. The evening featured several lightning talks on a range of topics, from breaking into data science to network visualization to starting your own blog. I gave a talk about sandwich standard errors and my clubSandwich R package. Here are links to some of the talks: Caitlin Hudon: Getting Plugged into Data Science Claire McWhite: A quick intro to networks Nathaniel Woodward: Blogdown Demo!

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Consider Pearson’s correlation coefficient, \(r\), calculated from two variables \(X\) and \(Y\) with population correlation \(\rho\). If one calculates \(r\) from a simple random sample of \(N\) observations, then its sampling variance will be approximately \[ \text{Var}(r) \approx \frac{1}{N}\left(1 - \rho^2\right)^2. \] But what if the observations are drawn from a multi-stage sample? If one uses the raw correlation between the observations (ignoring the multi-level structure), then the \(r\) will actually be a weighted average of within-cluster and between-cluster correlations (see Snijders & Bosker, 2012).

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The delta method is surely one of the most useful techniques in classical statistical theory. It’s perhaps a bit odd to put it this way, but I would say that the delta method is something like the precursor to the bootstrap, in terms of its utility and broad range of applications—both are “first-line” tools for solving statistical problems. There are many good references on the delta-method, ranging from the Wikipedia page to a short introduction in The American Statistician (Oehlert, 1992).

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Recent Publications

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(2018). Small sample methods for cluster-robust variance estimation and hypothesis testing in fixed effects models. Journal of Business and Economic Statistics, 36(4), 672–683.

Preprint Journal R package

(2018). Between-case standardized effect size analysis of single case design: Examination of the two methods. Research in Developmental Disabilities, 79, 88-96.

Journal

(2018). A gradual effects model for single-case designs. Multivariate Behavioral Research, forthcoming.

Preprint Supplementary materials R package Web app Journal

(2018). Single-case synthesis tools II: Comparing overlap measures and parametric effect sizes for synthesizing antecedent sensory-based interventions. Research in Developmental Disabilities, 79, 65-76.

Journal

(2018). Single-case synthesis tools I: Evaluating the quality and rigor of research on antecedent sensory-based interventions. Research in Developmental Disabilities, 79, 19-32.

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Recent Presentations

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Combining robust variance estimation with models for dependent effect sizes
Combining robust variance estimation with models for dependent effect sizes
Meta-analysis of dependent effects: A review and consolidation of methods
Meta-analysis of single-case research: A brief and breezy tour
A gradual effects model for single case designs

Software

ARPobservation

Simulate systematic direct observation data.

SingleCaseES

Single-case design effect size calculator.

clubSandwich

cluster-robust variance estimation.

scdhlm

Between-case SMD for single-case designs.

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