The effect of the individual (percentage of daylight, glass cover thickness,
initial water depth, water salinity), and their interactions on the distillate
output were statistically analyzed. A simple statistical program was
developed, utilizing the SAS packages. The correlation and stepwise
regression analyses were applied to find a reasonable good set of the independent variables.
The criterion for adding or deleting an independent variable can be stated
equivalently in terms of error of square reduction, coefficient of partial
correlation, or F statistics. Table (2) shows the final regression model with
the set of independent variables.