The Smart Forecaster
Pursuing best practices in demand planning,
forecasting and inventory optimization
Improve Forecast Accuracy, Eliminate Excess Inventory, & Maximize Service Levels
In this video, Dr. Thomas Willemain, co-Founder and SVP Research, talks about improving Forecast Accuracy by Managing Error. This video is the first in our series on effective methods to Improve Forecast Accuracy. We begin by looking at how forecast error causes pain and the consequential cost related to it. Then we will explain the three most common mistakes to avoid that can help us increase revenue and prevent excess inventory. Tom concludes by reviewing the methods to improve Forecast Accuracy, the importance of measuring forecast error, and the technological opportunities to improve it.
Forecast error can be consequential
Consider one item of many
- Product X costs $100 to make and nets $50 profit per unit.
- Sales of Product X will turn out to be 1,000/month over the next 12 months.
- Consider one item of many
What is the cost of forecast error?
- If the forecast is 10% high, end the year with $120,000 of excess inventory.
- 100 extra/month x 12 months x $100/unit
- If the forecast is 10% low, miss out on $60,000 of profit.
- 100 too few/month x 12 months x $50/unit
Three mistakes to avoid
1. Ignoring error.
- Unprofessional, dereliction of duty.
- Wishing will not make it so.
- Treat accuracy assessment as data science, not a blame game.
2. Tolerating more error than necessary.
- Statistical forecasting methods can improve accuracy at scale.
- Improving data inputs can help.
- Collecting and analyzing forecast error metrics can identify weak spots.
3. Wasting time and money going too far trying to eliminate error.
- Some product/market combinations are inherently more difficult to forecast. After a point, let them be (but be alert for new specialized forecasting methods).
- Sometimes steps meant to reduce error can backfire (e.g., adjustment).
What is the wiggle effect? It’s when your statistical forecast incorrectly predicts the ups and downs observed in your demand history when there really isn’t a pattern. It’s important to make sure your forecasts don’t wiggle unless there is a real pattern. Here is a transcript from a recent customer where this issue was discussed:
Smart Software’s article has won 1st place in the 2022 Supply Chain Brief MVP Awards Forecasting category!
Smart Software is pleased to announce that our article “Managing Inventory amid Regime Change” has won 1st place in the Forecasting category of the 2022 Supply Chain Brief MVP Awards.
CFOs tell us they need to spend less on inventory without impacting sales. One way to do that is to move away from using targeted day of supply rules to determine reorder points and safety stock buffers. Here is how a target days of supply/coverage approach works: