Posts

A colleague and her students asked me the other day whether I knew of a citation that gives the covariance between the sample variances of two outcomes from a common sample.

Parker, Vannest, Davis, and Sauber (2011) proposed Tau-U as an effect size measure for use in single-case designs that exhibit baseline trend. In their original paper, they actually conceptualize Tau-U as a family of four distinct indices, distinguished by a) whether the index includes an adjustment for the presence of baseline trend and b) whether the index incorporates information about trend during the intervention phase.

Parker and Vannest (2009) proposed non-overlap of all pairs (NAP) as an effect size index for use in single-case research. NAP is defined in terms of all pair-wise comparisons between the data points in two different phases for a given case (i.

Regression discontinuity designs (RDDs) are now a widely used tool for program evaluation in economics and many other fields. RDDs occur in situations where some treatment/program of interest is assigned on the basis of a numerical score (called the running variable), all units scoring above a certain threshold receiving treatment and all units scoring at or below the threshold having treatment withheld (or vice versa, with treatment assigned to units scoring below the threshold).

NOTE (2019-09-24): This post pertains to version 0.56 of the rdd package. The problems described in this post have been corrected in version 0.57 of the package, which was posted to CRAN on 2016-03-14.

I’ve recently been working with my colleague Beth Tipton on methods for cluster-robust variance estimation in the context of some common econometric models, focusing in particular on fixed effects models for panel data—or what statisticians would call “longitudinal data” or “repeated measures.

Yesterday evening I again had the pleasure of visiting Dr. Barnes’ pro seminar for first year students in Special Education, where I shared some of my work on research synthesis and meta-analysis of single-case research.

Several students and colleagues have asked me recently about an issue that comes up in multivariate meta-analysis when some of the studies include multiple treatment groups and multiple outcome measures.

I have been hearing quite a bit lately about how there have been an unusually large number of fatal automobile crashes in Austin this year, resulting in a total of 69 fatalities (as of August 19th).

I’ve recently been working on small-sample correction methods for hypothesis tests in linear regression models with cluster-robust variance estimation. My colleague (and grad-schoolmate) Beth Tipton has developed small-sample adjustments for t-tests (of single regression coefficients) in the context of meta-regression models with robust variance estimation, and together we have developed methods for multiple-contrast hypothesis tests.