| 1. |
- Akiyama, Kazunori, et al.
(författare)
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First Sagittarius A* Event Horizon Telescope Results. II. EHT and Multiwavelength Observations, Data Processing, and Calibration
- 2022
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Ingår i: Astrophysical Journal Letters. - : American Astronomical Society. - 2041-8213 .- 2041-8205. ; 930:2
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Tidskriftsartikel (refereegranskat)abstract
- We present Event Horizon Telescope (EHT) 1.3 mm measurements of the radio source located at the position of the supermassive black hole Sagittarius A* (Sgr A*), collected during the 2017 April 5-11 campaign. The observations were carried out with eight facilities at six locations across the globe. Novel calibration methods are employed to account for Sgr A*'s flux variability. The majority of the 1.3 mm emission arises from horizon scales, where intrinsic structural source variability is detected on timescales of minutes to hours. The effects of interstellar scattering on the image and its variability are found to be subdominant to intrinsic source structure. The calibrated visibility amplitudes, particularly the locations of the visibility minima, are broadly consistent with a blurred ring with a diameter of similar to 50 mu as, as determined in later works in this series. Contemporaneous multiwavelength monitoring of Sgr A* was performed at 22, 43, and 86 GHz and at near-infrared and X-ray wavelengths. Several X-ray flares from Sgr A* are detected by Chandra, one at low significance jointly with Swift on 2017 April 7 and the other at higher significance jointly with NuSTAR on 2017 April 11. The brighter April 11 flare is not observed simultaneously by the EHT but is followed by a significant increase in millimeter flux variability immediately after the X-ray outburst, indicating a likely connection in the emission physics near the event horizon. We compare Sgr A*'s broadband flux during the EHT campaign to its historical spectral energy distribution and find that both the quiescent emission and flare emission are consistent with its long-term behavior.
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| 2. |
- Brown, Nicholas, 1960-, et al.
(författare)
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A critical reanalysis of the relationship between genomics and well-being
- 2014
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 111:35, s. 12705-12709
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Tidskriftsartikel (refereegranskat)abstract
- Fredrickson et al. [Fredrickson BL, et al. (2013) Proc Natl Acad Sci USA 110(33):13684–13689] claimed to have observed significant differences in gene expression related to hedonic and eudaimonic dimensions of well-being. Having closely examined both their claims and their data, we draw substantially different conclusions. After identifying some important conceptual and methodological flaws in their argument, we report the results of a series of reanalyses of their dataset. We first applied a variety of exploratory and confirmatory factor analysis techniques to their self-reported well-being data. A number of plausible factor solutions emerged, but none of these corresponded to Fredrickson et al.’s claimed hedonic and eudaimonic dimensions. We next examined the regression analyses that purportedly yielded distinct differential profiles of gene expression associated with the two well-being dimensions. Using the best-fitting two-factor solution that we identified, we obtained effects almost twice as large as those found by Fredrickson et al. using their questionable hedonic and eudaimonic factors. Next, we conducted regression analyses for all possible two-factor solutions of the psychometric data; we found that 69.2% of these gave statistically significant results for both factors, whereas only 0.25% would be expected to do so if the regression process was really able to identify independent differential gene expression effects. Finally, we replaced Fredrickson et al.’s psychometric data with random numbers and continued to find very large numbers of apparently statistically significant effects. We conclude that Fredrickson et al.’s widely publicized claims about the effects of different dimensions of well-being on health-related gene expression are merely artifacts of dubious analyses and erroneous methodology.
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| 3. |
- Brown, Nicholas, 1960-, et al.
(författare)
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A Reproduction of the Results of Onyike et al. (2003)
- 2021
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Ingår i: Meta-Psychology. - : Linnaeus University Press. - 2003-2714. ; 5
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Tidskriftsartikel (refereegranskat)abstract
- Onyike et al. (2003) analyzed data from a large-scale US-American data set, the Third National Health and Nutrition Examination Survey (NHANES-III), and reported an association between obesity and major depression, especially among people with severe obesity. Here, we report the results of a detailed replication of Onyike et al.’s analyses. While we were able to reproduce the majority of these authors’ descriptive statistics, this took a substantial amount of time and effort, and we found several minor errors in the univariate descriptive statistics reported in their Tables 1 and 2. We were able to reproduce most of Onyike et al.’s bivariate findings regarding the relationship between obesity and depression (Tables 3 and 4), albeit with some small discrepancies (e.g., with respect to the magnitudes of standard errors). On the other hand, we were unable to reproduce Table 5, containing Onyike et al.’s findings with respect to the relationship between obesity and depression when controlling for plausible confounding variables—arguably the paper’s most important results—because some of the included predictor variables appear to be either unavailable, or not coded in the way reported by Onyike et al., in the public NHANES-III data sets. We discuss the implications of our findings for the transparency of reporting and the reproducibility of published results.
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| 4. |
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| 5. |
- Brown, Nicholas, 1960-, et al.
(författare)
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Does Twitter language reliably predict heart disease? : A commentary on Eichstaedt et al. (2015a)
- 2018
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Ingår i: PeerJ. - : PeerJ. - 2167-8359. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We comment on Eichstaedt et al.’s (2015a) claim to have shown that language patterns among Twitter users, aggregated at the level of US counties, predicted county-level mortality rates from atherosclerotic heart disease (AHD), with “negative” language being associated with higher rates of death from AHD and “positive” language associated with lower rates. First, we examine some of Eichstaedt et al.’s apparent assumptions about the nature of AHD, as well as some issues related to the secondary analysis of online data and to considering counties as communities. Next, using the data files supplied by Eichstaedt et al., we reproduce their regression- and correlation-based models, substituting mortality from an alternative cause of death—namely, suicide—as the outcome variable, and observe that the purported associations between “negative” and “positive” language and mortality are reversed when suicide is used as the outcome variable. We identify numerous other conceptual and methodological limitations that call into question the robustness and generalizability of Eichstaedt et al.’s claims, even when these are based on the results of their ridge regression/machine learning model. We conclude that there is no good evidence that analyzing Twitter data in bulk in this way can add anything useful to our ability to understand geographical variation in AHD mortality rates.
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| 6. |
- Brown, Nicholas, 1960-, et al.
(författare)
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Easy as (Happiness) Pie? : A Critical Evaluation of a Popular Model of the Determinants of Well-Being
- 2020
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Ingår i: Journal of Happiness Studies. - : Springer. - 1389-4978 .- 1573-7780. ; 21:4, s. 1285-1301
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Tidskriftsartikel (refereegranskat)abstract
- An underlying principle behind much of the research in positive psychology is that individuals have considerable leeway to increase their levels of happiness. In an influential article that is frequently cited in support of such claims, Lyubomirsky et al. (Rev Gen Psychol 9:111–131, 2005. https://doi-org.proxy.lnu.se/10.1037/1089-2680.9.2.111) put forward a model (subsequently popularized under the name of the “happiness pie”) in which approximately 50% of individual differences in happiness are due to genetic factors and 10% to life circumstances, leaving 40% available to be changed via volitional activities. We re-examined Lyubomirsky et al.’s claims and found several apparent deficiencies in their chain of arguments on both the empirical and the conceptual level. We conclude that there is little empirical evidence for the variance decomposition suggested by the “happiness pie,” and that even if it were valid, it is not necessarily informative with respect to the question of whether individuals can truly exert substantial influence over their own chronic happiness level. We believe that our critical re-examination of Lyubomirsky et al.’s seminal article offers insights into some common misconceptions and pitfalls of scientific inference, and we hope that it might contribute to the construction of a more rigorous and solid empirical basis for the field of positive psychology.
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| 7. |
- Brown, Nicholas, 1960-, et al.
(författare)
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Emodiversity : Robust Predictor of Outcomes or Statistical Artifact?
- 2017
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Ingår i: Journal of experimental psychology. General. - : American Psychological Association (APA). - 0096-3445 .- 1939-2222. ; 146:9, s. 1372-1378
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Tidskriftsartikel (refereegranskat)abstract
- This article examines the concept of emodiversity, put forward by Quoidbach et al. (2014) as a novel source of information about "the health of the human emotional ecosystem" (p. 2057). Quoidbach et al. drew an analogy between emodiversity as a desirable property of a person's emotional make-up and biological diversity as a desirable property of an ecosystem. They claimed that emodiversity was an independent predictor of better mental and physical health outcomes in two large-scale studies. Here, we show that Quoidbach et al.'s construct of emodiversity suffers from several theoretical and practical deficiencies, which make these authors' use of Shannon's (1948) entropy formula to measure emodiversity highly questionable. Our reanalysis of Quoidbach et al.' s two studies shows that the apparently substantial effects that these authors reported are likely due to a failure to conduct appropriate hierarchical regression in one case and to suppression effects in the other. It appears that Quoidbach et al.' s claims about emodiversity may reduce to little more than a set of computational and statistical artifacts.
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| 8. |
- Brown, Nicholas, 1960-, et al.
(författare)
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More Questions than Answers : Continued Critical Reanalysis of Fredrickson et al.'s Studies of Genomics and Well-Being
- 2016
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 11:6
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Tidskriftsartikel (refereegranskat)abstract
- We critically re-examine Fredrickson et al.’s renewed claims concerning the differential relationship between hedonic and eudaimonic forms of well-being and gene expression, namely that people who experience a preponderance of eudaimonic well-being have gene expression profiles that are associated with more favorable health outcomes. By means of an extensive reanalysis of their data, we identify several discrepancies between what these authors claimed and what their data support; we further show that their different analysis models produce mutually contradictory results. We then show how Fredrickson et al.’s most recent article on this topic not only fails to adequately address our previously published concerns about their earlier related work, but also introduces significant further problems, including inconsistency in their hypotheses. Additionally, we demonstrate that regardless of which statistical model is used to analyze their data, Fredrickson et al.’s method can be highly sensitive to the inclusion (or exclusion) of data from a single subject. We reiterate our previous conclusions, namely that there is no evidence that Fredrickson et al. have established a reliable empirical distinction between their two delineated forms of well-being, nor that eudaimonic well-being provides any overall health benefits over hedonic well-being.
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| 9. |
- Brown, Nicholas, 1960-, et al.
(författare)
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Positive Psychology and Romantic Scientism
- 2014
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Ingår i: American Psychologist. - : American Psychological Association (APA). - 0003-066X .- 1935-990X. ; 69:6, s. 636-637
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Tidskriftsartikel (refereegranskat)abstract
- Replies to the comments of Nickerson (see record 2014-36500-010), Guastello (see record 2014-36500-011), Musau (see record 2014-36500-013), Hämäläinen et al. (see record 2014-36500-014), and Lefebvre and Schwartz (see record 2014-36500-015) on the authors article (see record 2013-24609-001). Fredrickson and Losada’s (2005) article was the subject of over 350 scholarly citations before our critique (Brown et al., 2013) appeared, and its principal “conclusions” have been featured in many lectures and public presentations by senior members of the positive psychology research community, although its deficiencies ought to have been visible to anyone with a modest grasp of mathematics and a little curiosity. Unfortunately— because human behavior is, after all, complex and difficult to understand—we have no way of knowing whether the fact that it took so long for these deficiencies to be recognized was due to an unwarranted degree of optimism about the reliability of the peer-review process, a reluctance to make waves in the face of powerful interests, a general lack of critical thinking within positive psychology, or some other factor. We hope that our revelation of the problems with the critical positivity ratio ultimately demonstrates the success of science as a self-correcting endeavor; however, we would have greatly preferred it if our work had not been necessary in the first place.
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| 10. |
- Brown, Nicholas, 1960-, et al.
(författare)
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Questionable Measures Are Pretty Meaningless
- 2015
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Ingår i: American Psychologist. - : American Psychological Association (APA). - 0003-066X .- 1935-990X. ; 70:6, s. 571-573
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Tidskriftsartikel (refereegranskat)abstract
- Comments on the original article "Life is pretty meaningful," by S. J. Heintzelman and L. A. King (see record 2014-03265-001). Heintzelman and King argued that meaning in life (MIL) is widely experienced and exists at high levels. In this brief commentary, the current authors examine what they believe are several flaws in their argument: a lack of clarity in defining MIL; the questionable validity of the instruments used to measure MIL throughout Heintzelman and King’s article; and an erroneous interpretation of quantitative reports of MIL from surveys and the academic literature.
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