# SSL: Safety stock over lead-time In SCperf: Supply Chain Perform

### Description

SSL computes the safety stock level over lead-time for three forecasting methods: Minimum Mean Square Error (MMSE), Simple Moving Average (SMA) and Exponential Smoothing (ES) when the demand follows a stationary AR(1) stochastic process.

### Usage

 1 SSL(method = c("MMSE", "SMA", "ES"), phi, L, p, alpha, SL) 

### Arguments

 method character string specifing which forecasting method to use, phi a vector of autoregressive parameters, L a positive lead-time, p the order to be used in the SMA method, alpha smoothing factor to be used in the ES method (0 < alpha < 1), SL service level.

### Details

SSL is calculated using an estimate of the standard deviation of forecasting error for lead-time demand √{Var(D_t^L-\hat{D}_t^L)} where \hat{D}_t^L is an estimate of the mean demand over L periods after period t.

### Value

The safety stock level over the lead-time.

### Author(s)

Marlene Silva Marchena marchenamarlene@gmail.com

### References

Silva Marchena, M. (2010) Measuring and implementing the bullwhip effect under a generalized demand process. http://arxiv.org/abs/1009.3977

Zhang, X. The impact of forecasting methods on the bullwhip effect, International Journal of Production Economics.l, v.88, n.1, p. 15-27, 2004a.

SCperf

### Examples

 1 2 3 4 5 SSL("MMSE",0.15,2,4,0.7,0.95) SSL("SMA",0.15,2,4,0.7,0.95) SSL("ES",0.15,2,4,0.7,0.95) 

SCperf documentation built on May 19, 2017, 9:37 p.m.

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