Simpson's Paradox is suppression, but Lord's Paradox is neither: clarification of and correction to Tu, Gunnell, and Gilthorpe (2008).

Tu et al. (Emerg Themes Epidemiol 5:2, 2008. https://doi.org/10.1186/1742-7622-5-2) asserted that suppression, Simpson's Paradox, and Lord's Paradox are all the same phenomenon-the reversal paradox. In the reversal paradox, the association between an outcome variable and an explanatory (predictor) variable is reversed when another explanatory variable is added to the analysis. More specifically, Tu et al. (2008) purported to demonstrate that these three paradoxes are different manifestations of the same phenomenon, differently named depending on the scaling of the outcome variable, the explanatory variable, and the third variable. According to Tu et al. (2008), when all three variables are continuous, the phenomenon is called suppression; when all three variables are categorical, the phenomenon is called Simpson's Paradox; and when the outcome variable and the third variable are continuous but the explanatory variable is categorical, the phenomenon is called Lord's Paradox. We show that (a) the strong form of Simpson's Paradox is equivalent to negative suppression for a 2 × 2 × 2 contingency table, (b) the weak form of Simpson's Paradox is equivalent to classical suppression for a 2 × 2 × 2 contingency table, and (c) Lord's Paradox is not the same phenomenon as suppression or Simpson's Paradox.

No empirical evidence for critical positivity ratios.

Comments on the article by Fredrickson and Losada (see record 2005-11834-001). Fredrickson (2013) herself, in reply to Brown et al. (2013), remarked that "most valuable to the maturation of this work will be longitudinal field studies and experiments that use densely repeated measures of emotions and relevant outcomes" (p. 820). This remark raises the question of why, if Fredrickson understands that a longitudinal (within-person across-time) study is needed to test the theory, this was not acknowledged in the initial article (Fredrickson & Losada, 2005), in the book that highlights the research of that article (Fredrickson, 2009, Chapter 7), or in the correction to the original article (Fredrickson & Losada, 2013), the latter of which insisted on the validity of the results of Fredrickson and Losada's (2005) within time across-persons study. Indeed, why wasn't the appropriate study design used in the first place? After all, it has been pointed out many times over many years that the data and the analysis used to test a theory should correspond to that theory and that a test of a within-person theory nearly always requires within-person data and analysis. Doing research the wrong way, while delaying doing it the right way "until later," is not acceptable after so many years of discussions of this issue.

Altruism, incentives, and organ donation: attitudes of the transplant community.

OBJECTIVES: This study investigated the attitudes of the transplant community toward the current policy of altruistic organ donation and 6 alternative policies offering incentives to the donor family. METHODS: Two hundred forty-nine transplant surgeons, 143 transplant coordinators, and 134 critical-care nurses rated the moral appropriateness and success of the current policy of altruistic donation, rated the moral appropriateness of the alternative policies, judged whether donation would increase or decrease under each alternative policy, and decided whether each alternative policy should be put into effect. RESULTS: All 3 professions believed the current policy of altruistic organ donation to be morally appropriate and most of the alternative policies to be morally appropriate or morally neutral. All 3 professions believed the current policy to be at best only moderately successful and judged most or all of the alternative policies to be likely to increase donation. All 3 professions favored implementing a policy offering donor recognition; approximately one half of the surgeons and one half of the coordinators also advocated implementing a policy offering 1500 US dollars toward funeral expenses. In all 3 professions, respondents' decisions to implement the alternative policies were more frequently related to those policies' moral appropriateness than to their likelihood of increasing organ donation. CONCLUSIONS: Specific incentives varied in their acceptability to the transplant community. Attitudes of the transplant community toward incentives were not in accord with published criticisms of incentives.