Statistical discussion on the circle chart “Bat’s Wing” by Nightingale as a statistician

Abstract

Data on the number of deaths by cause of death of soldiers in a field hospital and the circle chart “Bat’s Wing (B.W.)” recorded by Nightingale during the Crimean War were examined from the angle of statistics. Nightingale showed by B.W. that the number of soldiers dying from epidemics due to poor sanitation was far greater than the number dying from combat injuries. This study focused on the number of deaths due to infectious diseases and created a B.W. The number of patients dying from infectious diseases showed a significant positive correlation with the number of patients dying from injuries or from other causes. On the other hand, there was no significant relationship between the number of soldiers who died from infectious diseases and the number of troops. A multiple regression model with season as a dummy variable revealed that the number of deaths due to infectious diseases is strongly related not only to poor sanitation, but also to the season (summer). The area of the triangle for each month created by B.W. (B.W. area) was significantly correlated with the number of infectious disease deaths per month. The B.W. area seems to be a mathematical property of B.W. The B.W. area was also significantly correlated with the estimated number of deaths due to infectious diseases, calculated from the number of deaths due to injuries and the number of deaths due to other causes. This correlation was a pseudo-correlation with the number of infectious disease deaths as a confounding factor.