The coefficient of determination (R2) and
the ratio of the root mean square error to the standard deviation of
observed data (RSR) were used to analyze the correlation between the
observed and predicted drop shapes during the fall. The ranges of R2
and RSR values are from−∞to 1.0 and+∞ to 0, respectively. Acceptable
values of R2 and RSR are from 0 to 1.0 and close to 0, respectively (see
Moriasi et al., 2007).