What you will be able to do
- Reconcile moisture-adjusted physical flows and calculate cost per saleable kilogram.
- Separate actor margins, chain resource costs and working-capital finance.
- Evaluate a loss-reduction intervention using incremental value and a credible measurement plan.
Before you begin: Basic percentages, unit costs and simple interest calculations.
Specify the batch, grade and decision perspective
Before calculating a margin, define what crosses your system boundary. Our unit is one purchased batch followed through drying, handling, sale and collection. The saleable product has a specified grade and a moisture content of twelve point five percent measured on a wet basis. We initially take the trader's financial perspective, so the purchase payment is a cost to that trader. A whole-chain analysis later needs a different treatment of transactions between actors. Record where ownership and risk transfer, because the party paying for an improvement may not capture its benefits. Without this boundary, analysts often mix farmgate quantities, wholesale prices and retailer costs in a single ratio that has no coherent operational meaning.
Use the correct stage denominator
Now apply a separate physical handling loss of two percent to the batch after moisture adjustment. Multiplying nine hundred and fourteen point two nine by ninety-eight percent gives exactly eight hundred and ninety-six saleable kilograms before rounding. That denominator is part of the assumption: the two percent refers to the target-moisture stage, not to the original wet purchase weight. If a supplier reports a combined shrink allowance, unpack it before adding another handling-loss assumption. Otherwise you may charge the same loss twice. Reconcile opening mass with water removed, physical loss and closing saleable mass. Where actual observations do not reconcile, investigate measurement timing and scale calibration before interpreting the residual as theft or operational waste.
A transfer between actors is not a new chain resource cost
Our trader's purchase cost is another actor's revenue. If you aggregate the whole chain, adding every purchase payment to every actor's production costs would double count internal transactions. Build an actor-by-actor account first, then eliminate transfers inside the chosen boundary when estimating total resource use. Keep external inputs, labour and other relevant resources under clearly stated valuation assumptions. Distribution still matters: an intervention can raise total chain surplus while leaving the actor who must finance it worse off. Map the payment mechanism, contract terms and bargaining position. That analysis may suggest shared investment, a price premium or a service fee. Do not assume that a technically efficient intervention will be adopted merely because the aggregate arithmetic looks attractive.
Turn uncertainty into a testable decision condition
Thresholds help prioritise field evidence. Including the assumed financing cost, divide total cost by eight hundred and ninety-six kilograms to find a break-even price of about five point five one five seven cedis. A ten percent fall from the six-cedi selling price gives five point four, producing a loss of roughly one hundred and three point six three. For the eighty-cedi intervention, divide its cost by the moisture-adjusted quantity times the six-cedi price. It needs approximately one point four five eight three percentage points of physical-loss reduction to break even, if no other benefit changes. Starting at two percent loss, that means ending at about zero point five four one seven percent. These are specific conditions to test, not universal performance targets.
Apply the method
Work through each task before opening the model answer. Compare your reasoning with the review criteria. Written answers stay on this page and clear when you leave or reload it.
Applied task 1
Show model answer and review criteria
Dry matter 800 kg; target-moisture mass 914.2857 kg; saleable output 896 kg after 2% handling loss. Cost 4,800, revenue 5,376, pre-finance surplus 576. Assuming all costs financed upfront for 45 days at 24% simple annual interest on 365 days, finance is 142.0274 and post-finance surplus 433.9726 GHS.
- Mass balance distinguishes water removal and physical loss
- Correct saleable unit cost, revenue and surplus
- Explicit upfront funding, collection date and simple-interest assumptions
Applied task 2
Show model answer and review criteria
At a 1-point reduction, recovered value is 54.8571 and net effect −25.1429 GHS. Break-even requires 1.4583 percentage points of loss reduction, or an equivalent additional evidenced benefit. Compare batches at equal moisture, grade and duration; retain identifiers and missing batches. Quantify any grade premium or avoided rejection and identify whether the paying actor captures it.
- Correct incremental calculation and break-even threshold
- Comparable-batch plan with moisture and denominator controls
- Additional benefit documented without double counting and allocated to an actor
Method references
- Purdue Cooperative Extension — Calculating Grain Weight Shrinkage in Corn Due to Mechanical Drying
Distinguishing water removal from physical handling loss and conserving dry matter; quantities, costs and intervention calculations are original hypothetical examples.