planning demand and supply in a supply chain forecasting and aggregate planning
TRANSCRIPT
Planning Demand and Supply in a Supply Chain
Forecasting and Aggregate Planning
供應鏈的需求預測
供應鏈決策的階層界定需求預測的要項時間數列預測法估算預測的誤差
Learning ObjectivesPhases of supply chain decisions
Identify components of a demand forecast
Time series forecasting
Estimate forecast error
供應鏈決策的階層Phases of Supply Chain Decision
s策略性 Strategy or design: 預測 Forecast
計畫性 ( 戰術性 )Planning:預測 Forecast
作業性 Operation 實際需求 Actual demand
Characteristics of forecasts
Forecasts are always wrong. Should include expected value and measure of error.Long-term forecasts are less accurate than short-term forecasts: Forecast horizonAggregate forecasts are more accurate than disaggregate forecasts
Forecasting Methods
Qualitative
Time SeriesStatic Adaptive
Causal
Simulation
Components of an observation
Observed demand (O) =
Systematic component (S) + Random component (R)
Level (current deseasonalized demand)
Trend (growth or decline in demand)
Seasonality (predictable seasonal fluctuation)
Time Series Forecasting
Quarter Demand Dt II, 1998 8000 III, 1998 13000 IV, 1998 23000 I, 1999 34000 II, 1999 10000 III, 1999 18000 IV, 1999 23000 I, 2000 38000 II, 2000 12000 III, 2000 13000 IV, 2000 32000 I, 2001 41000
Forecast demand for thenext four quarters.
Time Series Forecasting
0
10,000
20,000
30,000
40,000
50,000
97,2
97,3
97,4
98,1
98,2
98,3
98,4
99,1
99,2
99,3
99,4
00,1
Forecasting methodsStatic Ft+l =[ L + (t+l)T ] St+l
AdaptiveFt+l =[ Lt + lTt ] St+l
Moving averageSimple exponential smoothingHolt’s model (with trend)Winter’s model (with trend and seasonalit
y)Excel File
Error measures
MAD
Mean Squared Error (MSE)
Mean Absolute Percentage Error (MAPE)
Bias
Tracking Signal