A useful yield forecast gives a planner time to prepare for a plausible crop quantity, not a promise that the crop will deliver it. Start with the product being counted and the person who can use the estimate. A prediction should support a review, not stand in for an observed harvest.
Start with the planning decision, not the model
Imagine a hypothetical greenhouse growing cucumbers. The packing lead wants to review next week's staffing before the roster closes. The grower can describe current crop condition, but the amount reaching the agreed grade remains uncertain. The business needs an estimate early enough to inform a choice, with a clear account of what could change.
- User
- Packing lead, with crop interpretation from the grower.
- Decision
- Review possible staffing arrangements before the roster closes.
- Product
- Net kilograms assigned to local planning grade P-v1 at the grading/weighing checkpoint in one identified zone.
- Limit
- The estimate does not approve staffing, change crop controls or make a customer commitment.
Choose a quantity that matches that decision. Total crop weight is not automatically the same as graded packing output. A weekly total also says little about which day may be busy. If the decision needs daily quantities, specify those separately rather than dividing a weekly prediction equally across seven days.
Ask what the user could do differently after seeing the forecast. If every staffing choice is already fixed before the issue time, a more accurate number may arrive too late to matter. The first improvement might be an earlier review, not a more complex model.
Kilograms alone do not state how many people or hours are needed: packing tasks, crew capability, equipment availability and the distribution of work across days would need their own local capacity assumptions. No such conversion is supplied here.
Freeze the definition before comparing estimates
In FP18-01, suppose the forecast is issued each Monday at 08:00 in the site's named time zone. Its target runs from the following Thursday at 00:00 up to, but not including, the next Thursday at 00:00. This invented schedule is a specification example, not a recommended crop horizon. Another operation may need a different lead time.
| Field | What must be fixed |
|---|---|
| Crop and place | Cultivar, crop group and zone included; record any change in membership. |
| Quantity | Net kilograms assigned P-v1 at the grading/weighing checkpoint, during the target window. |
| Window | Thursday 00:00 inclusive to the next Thursday 00:00 exclusive; record the actual time zone. |
| Issue | Forecast issue time, information cutoff and version. |
| Actual | Grading/weighing events within that window, with grade rule and closing/revision policy. |
The event defining this target is grading/weighing, not the time the fruit was picked or dispatched. This local planning grade does not establish food-safety clearance, customer acceptance or available stock. Crop variety and the actual grade criteria remain local choices to document, not facts supplied by this scenario.
Keep later changes visible. If the grade rule changes, the next result may represent a different target even when the column still says yield. Do not quietly rewrite earlier forecasts to match a new definition. Preserve which rule each forecast and actual used, then decide whether they can be compared.
This article concerns estimates made before the outcome. The separate task of reconciling harvested, trimmed, held and packed quantities still matters, but a prediction cannot repair an undefined actual.
Rebuild what was known at the issue time
Kaufman and colleagues' leakage paper explains why prediction information needs legitimate timing. For FP18-01, a Sunday inspection entered after Monday's cutoff was unavailable to the original issue.
- Retain event time, availability time and corrections.
- Freeze the eligible input snapshot.
- Issue the forecast; keep later updates separate.
- Attach the eventual actual without overwriting the estimate.
Unknown availability stays unknown. Use the weather forecast version available then, not later observed weather. Training outcomes must also have been available at the replayed issue. Fit preprocessing, feature choices and tuning on earlier development evidence, keeping later assessment outcomes separate.
Make the simple method a fair competitor
Forecasting: Principles and Practice describes evaluation using earlier training observations and later outcomes. Compare both methods at the required lead time.
| Window | Actual | Simple | Model |
|---|---|---|---|
| A | 120 | 100 | 115 |
| B | 80 | 100 | 95 |
| C | 110 | 100 | 90 |
| D | 90 | 100 | 120 |
Mean absolute error averages miss sizes, ignoring direction. Simple: (20 + 20 + 10 + 10) / 4 = 15 kg. Model: (5 + 15 + 20 + 30) / 4 = 17.5 kg. Here the model is worse. Four invented windows establish no crop performance. These arbitrary estimates define neither a fitted baseline nor a trained model.
For real evaluation, specify a simple candidate first, such as a locally reviewed recent-comparable-window estimate. Do not assume last week's quantity suits every crop stage.
Keep target, timing and assessed cases comparable; inspect overestimates and shortfalls separately. Repeated or overlapping windows are not independent crop trials. List every scheduled window, including missing predictions and pending actuals, before comparing.
Show a range with a meaning that can be checked
Gneiting and Raftery's scoring paper considers interval width and penalties for missed outcomes together. Simply making a range wider is not the whole assessment.
- Scenarios
- Low/base/high assumptions; no statistical coverage implied.
- Prediction interval
- State its method, intended coverage, target and lead time.
- Assessment
- Report assessed cases, observed coverage and width together.
- Unknown
- No validated range is claimed for FP18-01.
A broad range may include outcomes but distinguish no useful planning choice; a narrow one may miss too often. Check later comparable outcomes. A nominal coverage level is not achieved coverage or a guarantee for the next crop. A model's internal confidence number is not automatically a harvest probability.
Give the planner a usable brief, not a command
Return to the packing lead. A useful brief connects the estimate to a review time, the assumptions that matter and the choices still open. It should also say when it is unavailable. An old estimate carried forward silently may be more misleading than an explicit gap.
| Brief element | What the user receives |
|---|---|
| Estimate state | Issued time, target window, unit, method and current or unavailable status. |
| Evidence limits | Missing inspection, changed crop group or unresolved grade definition. |
| Review choices | Locally approved staffing options and the next decision deadline. |
| Decision record | Planner's choice, reason and later actual outcome, kept separately. |
A candidate prediction model might relate previous crop records to later graded quantity. For this brief, the analyst and grower would first ask whether crop age, represented plant count and recent grading history have useful, consistently defined records. No crop-specific relationship has been demonstrated here, and a predictive pattern is not permission to change growing conditions.
AI can help summarize the inputs and explain why a forecast changed. It must not invent a missing inspection, convert an uncertain estimate into a sales promise or claim the roster has changed when only a suggestion exists. Ordinary software is better suited to versioning, arithmetic and checking required fields.
Where information is unsuitable, show that state and use the locally approved manual review or fallback method. Do not automatically label the last prediction as current.
The crop register owns group identity. The existing grading record supplies the later quantity. A read-only forecast register retains the issued brief, while the packing plan records the human choice. This separation lets the lead ask what was predicted, what was decided and what happened without treating those as the same event.
A suggestion to move staff is not an acknowledged roster change. The planner still checks the local constraints and records whether to leave the plan alone, seek another crop observation or make an authorized revision. A changed plan alone does not prove a benefit.
Keep checking whether the forecast earns its place
Start with a retained comparison alongside the existing planning method. Set review questions before looking at the results: Did the estimate arrive in time? Was its target unchanged? Did it help the planner choose among real options? Did errors or unavailable forecasts create extra work?
- Timeliness
- Issued before the decision, not just before harvest.
- Comparison
- A linked assessment record, with its open issues.
- Completeness
- Every scheduled brief has a visible issued, unavailable or unassessed state.
- Usefulness
- The planner records whether the brief changed or supported a decision.
Revisit the comparison when crop membership, grade rules, growing methods or data collection change. A model that worked under one definition may not answer the new question.
At the review, ask the packing lead to walk through one real planning choice: what options were open, what the brief changed, and what still needed a human check. Keep this decision record even when the lead chose to leave the roster unchanged. It shows use, not proof of savings.
A pending grading record is unassessed, not zero yield. A confirmed zero is different again. Keep later corrections attached to the original actual and explain which version was used in a review. This is an outcome-status check, not a substitute for investigating crop losses.
The useful outcome is not that machine learning was installed. It is a clear, timely forecast the business can assess, challenge and use within its limits. It may remain an experiment rather than become a planning dependency.
