Abstract

Tau (τ), a nonparametric rank order correlation statistic, has been applied to single-case experimental designs with promising results. Tau-U, a family of related coefficients, partitions variance associated with changes in trend and level. By examining within-phase trend and across-phase differences separately with Tau-U, single-case investigators may gain useful descriptive and inferential insights about their data. Heuristic data sets were used to explore Tau-U’s conceptual foundation, and 115 published single-case data sets were analyzed to demonstrate that Tau-U coefficients perform predictably when they are well understood. An understanding of Tau-U’s theoretical basis and unique limitations will help investigators select the appropriate statistical method to test their hypotheses and interpret their results appropriately. Limitations of Tau-U include as follows: vague or inconsistent Tau-U terminology in published single-case research; arithmetic problems that lead to unexpected and difficult-to-interpret results, especially when controlling for baseline trend; Tau-U methods are difficult to graph visually, and a comparison with visual raters found that several Tau-U effect size statistics are weakly correlated with visual analysis.

Details

Title
Interpreting Kendall’s Tau and Tau-U for single-case experimental designs
Author
Brossart, Daniel F 1   VIAFID ORCID Logo  ; Laird, Vanessa C 1 ; Armstrong, Trey W 1 

 Department of Educational Psychology, Texas A&M University, USA 
Publication year
2018
Publication date
Jan 2018
Publisher
Taylor & Francis Ltd.
e-ISSN
23311908
Source type
Scholarly Journal
Language of publication
English
ProQuest document ID
2170827579
Copyright
© 2018 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license. This work is licensed under the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ (the “License”). Notwithstanding the ProQuest Terms and Conditions, you may use this content in accordance with the terms of the License.