2025-05-23
What was never counted...
The fundamental question
What we are going to do
Numerical experiment
What’s NEXT
UNSEEN
Human story
: What data missesNilu
went to a pharmacy for Product A. It was not in stock and the system logs it as zero demand.
When data is censored by stockouts or service interruptions… Forecasts fail… Not just by being wrong, but by being blind.
This creates broken trust and leads to UNMET DEMAND.
Analytical reality
: Why this mattersStockouts censor demand.
Observed sales ≠ actual demand.
Inventory decisions based on this false signal?
Understocking → more stockouts.
Forecasts don’t just underperform. They miss the whole story.
Contraceptives aren’t easily substitutable. A lost sale = a lost opportunity for care.
SUBSTITUTED
BIG PICTURE
In reality…
There are more than
218 million women
like Nilu still have an unmet need for family planning.
Ultimately, this results in dropouts, unwanted pregnancies, and almost 7 million hospitalizations
each year in developing countries.
critical
Stockouts
: Periods when demand is higher than available inventory, leading to censored observations of demand.
Interruptions
: Periods when no products are issued despite available stock, thus artificially recorded as zero demand.
Censored Demand
: Demand occurring during periods when products are unavailable (stockouts or interruptions), thus not fully observable.
True Demand
: Actual demand that would have occurred if sufficient stock was available or no interruptions happened.
How can a demand forecasting and inventory optimization model that incorporates lost sales estimation and contextual field data enhance contraceptive supply chain performance and reduce stockouts in developing countries?
Figure 1: Censorship scenarios in family planning supply chains.
First stage
: estimating true demand under censorship using tobit kalman filtering and conformal predictionFirst stage
: estimating true demand under censorship using tobit kalman filtering and conformal predictionexample
Actual vs. observed demand for one representative series per type × category, with disruptions and censoring shaded.
Method | MASE (mean) | Pin Ball Loss - q95 (mean) | CSL (mean) | Lost Sales Rate (mean) | Inventory Coverage (mean) |
---|---|---|---|---|---|
TKF CP | 0.87 | 47.61 | 0.86 | 0.14 | 5.25 |
Moving Average | 1.06 | 72.65 | 0.82 | 0.18 | 19.6 |
Linear Regression | 1.08 | 73.86 | 0.82 | 0.16 | 2.55 |
Naive | 1.21 | 78.89 | 0.84 | 0.16 | 123.38 |
Figure 2: Average ranks of forecasting methods with 95% confidence intervals based on the Nemenyi test for all metrics. Lower ranks indicate better performance.
Figure 3: Forecasting metrics for each series type for the different forecasting methods.
Figure 4: Inentory metrics for each series type for the different forecasting methods.
NEXT
Develop a quantile-based inventory policy → Incorporate uncertainty directly into order decisions
Extend empirical model with external covariates → Account for special events, disruptions, and policy shifts
Conduct lab experiment with real demand planners → Measure how model recommendations affect decision-making
You can find the slides here.