key: cord-0856715-i5e5a6xd authors: Lansiaux, Édouard; Pébaÿ, Philippe P.; Picard, Jean-Laurent; Forget, Joachim title: Response to Naudet et al. date: 2020-12-02 journal: Spat Spatiotemporal Epidemiol DOI: 10.1016/j.sste.2020.100388 sha: 24583462f96b4d5752546c5a91e739002a014ca8 doc_id: 856715 cord_uid: i5e5a6xd nan The correlation between vitamin D and sunlight exposure has been broadly documented and known for a long time 1 1. Our hypothesis was initially based upon COVID-19 outcomes differences between BAME (Black, Asian, Middle East) and White people living at the same latitudes , that could be explained by vitamin D deficiency in the BAME population 2 2. Links between vitamin D deficiency and COVID-19 fatal outcomes were widely documented since 3 3, it was not the case at the time of submission date. Furthermore, to assess this, the French National Academy of Medicine has recommended the rapid serum vitamin D (i.e. 25 OHD) testing in people over 60 years of age with Covid-19, and a loading dose of 50,000 to 100,000 IU in case of deficiency, which could help limit respiratory complications 4 4. Our manuscript 5 5 The sunlight exposure average has been measured since 2018 (not the same data as correspondents have used 6 6 ). Weather data are actually unreachable due to a recent website update 7 7. In more, COVID-19 outcomes data were extracted after the daily update so we have different numbers (as presented on our first manuscript), so the 25/05/2020 data were included in our manuscript and not in their letter and they were published online on the 26/05/2020 by Santé Publique France. Firstly, concerning the so-called mistake of «assumption of binormal distribution» 6 , we are sure that it has not escaped to the authors that we have used a Shapiro-Wilk test, as it is assessed in our previous manuscript and described in Table 1 . As a reminder, it is a test of normality in frequentist statistics which test the null hypothesis that a sample came from a normally distributed population. Monte Carlo simulation has found that Shapiro-Wilk test has the best power for a given significance 8 8. As the p-value for the sunlight exposure is 0.3697 (which is higher than the traditional 0,05 p-value and especially higher than the 0,001 p-value that we have fixed as the limit), we can't reject the null hypothesis. In this way, as we have assessed the normal distribution of each variable (including sunlight exposure), we don't violate any Pearson's correlation law because: 1) we have established the link between the sunlight exposure and the COVID-19 mortality (by r computation: R= -0.635688603). 2) We have obtained the regression line y = -55,459x + 2888,5. 3) According to our correspondents, if we use their analysis upon the 12 regions as N, we obtain t= 2.604 and a p-value of 0,0263 (the correlation stays significant with this p-value). In this way, the use of Spearman's correlation would be inappropriate here. In a second hand, we formally disagree on the follow statement «at least for sunlight exposure, since two neighboring regions have more similar climates than two distant regions» 6 . Indeed, for example in the «Provence-Alpes-Côte d'Azur» region, we can observe a diversity of climate (mountain, mediterranean); in more, «Auvergne-Rhônes-Alpes» region has mountain, but borderline regions have different climates (for instance, semi-oceanic and oceanic for «Nouvelle-Aquitaine» region) 9 9. To prove this statement, firstly, we invite our opponents to use of basic knowledges which assess that regions, with an average size of 43,925.875 km² ( Concerning the exclusion of the Corsican region, we have done it after the data extraction from the different public health already quoted in our manuscript 5 5. In order to justify, we used two indicators: the eldery equipment rate (in view of the large aged people infected by the COVID-19) and the hospitalization bed density (indeed, infected seniors require an hospitalization due to theirs comorbidities and not only a lockdown). Two of three trackers (the last one, the Corsican medical doctor density, had no significant difference with others regions) had significant differences with the others French regions (Tables 5 & 6) 5 5. Therefore, they have conducted us to exclude the Corsican region before the sunlight exposure data extraction (so it was an a priori choice), and not in order to «hack» the pvalue what we have been accused of. Finally, if our correspondents persist in their thesis of p-hacking, we will oppose them that their computed p-value 0,03 6 6. Using a ratione absurdum, this one stays above the usual medical significance threshold of 5%. In fact, thanks to this «negators» (according to the antique definition), even if we are wrong we are right. Therefore, we thank them for the fact that they, thus ,ensure the validity of our hypothesis, despite the mistakes they think have discovered. We are extremely enthusiastic about debating in a relaxing manner. Although the heart has its reasons that reason ignores, we must show restraint and rigor, especially in these sanitary hard times. This formal correspondence was very instructive for us (on modesty, respect...), we hope that it was and will for our correspondents. Male (%) Dependence between them Female (%) Biological Effects of Sunlight, Ultraviolet Radiation, Visible Light, Infrared Radiation and Vitamin D for Health Vitamin-D and COVID-19: do deficient risk a poorer outcome? The Lancet Covid-19 And Vit-D: Disease Mortality Negatively Correlates With Sunlight Exposure Letter to the editor: Covid-19 and Vit-D: Disease mortality negatively correlates with sunlight exposure Bienvenue sur le nouveau site de Météo-France ! Power comparisons of Shapiro-Wilk, Kolmogrov-Smirnov, Lilliefors and Anderson-Darling tests Le climat en France métropolitaine Statisticians of the Centuries Les 13 nouvelles régions françaises