Page 587 - Trends in Science and Technology fo Sustainable Living

548 Fakultas Sains dan Teknologi
Universitas Terbuka (2023)

Coefficients Standard Error t Stat P-value Lower 95% Upper 95%
Intercept 393909,6 64275,18 6,128488 0,000281 245690,7886 542128,4284
Rainfall -94,5048 160,559 -0,5886 0,57237 -464,754438 275,7448966
Rainy days -6777,47 2533,61 -2,67503 0,028142 -12619,98983 -934,9583271

Partially, the effect of the number of rainy days on salt yields
looks more significant than the effect of rainfall on salt harvests,
indicated by the p-value of the number of rainy days (0,028), which
is lower than alpha (0,05). This analysis produced a formula that
can be used to estimate the salt harvest (Y’) as follows.

Y' = 393.909,6 - (94,5 × X ) - (6.777,5 × X ) + e (4)
1 2
The results of the predictions can only predict the ups and
downs (fluctuations) of sea salt yields in Cirebon and illustrate
that if rainfall (X ) and the number of rainy days (X ) increase, the
1 2
sea salt harvest (Y') will decrease and vice versa, indicated by the
negative value of the coefficient for rainfall and the number of rainy
days. In comparison between the actual value (blue line) and the
predicted results (red line) using the formula from multiple linear
regression (4), the error value of the model is relatively high (Table
6 and Figure 6), so the prediction accuracy is still low. Using rainfall
reanalysis data as a predictor can also result in low prediction
accuracy. The anomaly of Cirebon sea salt production in the last
five years, which has continued to experience a significant decline
compared to the harvest of Indramayu sea salt in a coastal area, is
also thought to have affected the low accuracy. However, in general,
the resulting fluctuation pattern is similar, so it is still feasible to be
used to predict sea salt yields. The accuracy of the method can
be improved by increasing the number of input data variables
or by adding other variables that have the potential to affect salt
yields. Other climatological variables that can be added include
air temperature, relative humidity, wind speed, and evaporation