1. Problem Definition
Indonesia is still importing 75% of the domestic soybean demand of 2.5 million tons. The high dependence on imported soybeans make the government was powerless when soybean prices rose due to the weakening of the rupiah against the U.S. dollar (U.S.). As we know that soybean is the basic ingredients for tofu and tempe which are the most popular food here. Now I try to made 12 months future cost estimation of imported soybean price and use a new alternative currency reference with gold that consider as stable currency.
2. Development of Feasible Alternatives
The predicted price will estimate by trendline from soybean price in oz gold value and by analyze SPC (Statistical Process Control).
3. Development Outcomes for Alternative
Below are the historical data of the average price of gold, exchange rate and soybean per month from Jan 2011 to Oct 2013:
4. Selection of Criteria
Convert the soybean price (USD/gram) into gold equivalent (oz or troy-ounce), so that soybean price will refer to gold price. The historical data and its 12 months trendline of monthly average price of soybean in gold equivalent (gram soybean/oz Gold) from Jan 2011 to October 2013 (actual data above) is presented in below.
Selected model which close to describe the forecast is polynomial order 5th with R-squared = 0.8529. The formula obtained is:
y = -5E-05x5 + 0.007x4 – 0.340x3 + 4.280x2 + 15.51x + 1459.
5. Analysis of the Alternatives
SPC analysis for data from the formula selected as below :
So thus obtained control chart graph as below :
From control chart above, we can accept since all the data are within UCL and LCL .
6. Selection of Preferred Alternative
Predicted value of gram soybean in 1 oz gold is : (x=46 ; 12 months from oct 2013) 1879.95 gram/oz gold (still within range UCL and LCL). From blog W8.2, the predicted average price for gold in 2014 from moderate formula is 1948.26 USD/oz gold. So, the predicted price of soybean 12 months onward or in oct 2014 is:
1948.26/1879.95 = 1.04 USD/gram
7. Performance Monitoring & Post Evaluation of Results
At this time, the value of the Rupiah continues to fall against the USD, make soybean import prices go up. If the price of imported soybean based on the price of gold the price of soybeans will be relatively more stable. Control chart analysis could be made better by predict the price range in the coming months with daily data.
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