R: Forecasts for intermittent demand using Croston's method

croston {forecast} | R Documentation

## Forecasts for intermittent demand using Croston's method

### Description

Returns forecasts and other information for Croston's forecasts applied to y.

### Usage

    croston(y, h = 10, alpha = 0.1, x = y)

### Arguments

`y` | a numeric vector or time series of class `ts`
`h` | Number of periods for forecasting.
`alpha` | Value of alpha. Default value is 0.1.
`x` | Deprecated. Included for backwards compatibility.

### Details

Based on Croston's (1972) method for intermittent demand forecasting, also described in Shenstone and Hyndman (2005). Croston's method involves using simple exponential smoothing (SES) on the non-zero elements of the time series and a separate application of SES to the times between non-zero elements of the time series. The smoothing parameters of the two applications of SES are assumed to be equal and are denoted by `alpha`.

Note that prediction intervals are not computed as Croston's method has no underlying stochastic model.

### Value

An object of class `"forecast"` is a list containing at least the following elements:

`model` | A list containing information about the fitted model. The first element gives the model used for non-zero demands. The second element gives the model used for times between non-zero demands. Both elements are of class `forecast`.
`method` | The name of the forecasting method as a character string
`mean` | Point forecasts as a time series
`x` | The original time series (either `object` itself or the time series used to create the model stored as `object`).
`residuals` | Residuals from the fitted model. That is y minus fitted values.
`fitted` | Fitted values (one-step forecasts)

The function `summary` is used to obtain and print a summary of the results, while the function `plot` produces a plot of the forecasts.

The generic accessor functions `fitted.values` and `residuals` extract useful features of the value returned by `croston` and associated functions.

### Author(s)

Rob J Hyndman

### References

Croston, J. (1972) "Forecasting and stock control for intermittent demands", Operational Research Quarterly, 23(3), 289-303.

Shenstone, L., and Hyndman, R.J. (2005) "Stochastic models underlying Croston's method for intermittent demand forecasting". Journal of Forecasting, 24, 389-402.

### See Also

`ses`.

### Examples

    y <- rpois(20,lambda=.3)
    fcast <- croston(y)
    plot(fcast)

[Package forecast version 8.12 Index]