I would to forecast a not-seasonal time serie in R. This is my serie and the model built with HoltWinters:

tsRedditoMedioForecast <- HoltWinters(redditoMedio, beta=FALSE, gamma=FALSE)

If beta and gamma parameters are FALSE, I built a Brown model that haven't seasonal component.

Time series and model with HoltWinters

For forecasting, I imported the library "forecast" in my workspace:

install.packages('forecast', dependencies = TRUE)

Last step: I would to forecast and calculate the value for the next 10 units. I put this R code:

tsRedditoMedioForecast2 <- forecast(tsRedditoMedioForecast, h=10)

The result is this: Forecasting time series But I don't expect this. Time serie is increasing, so I expect an increasing prediction line. Not an horizontal constant line. What's the problem?


I have expected results with ETS and auto.arima models

enter image description here

Why not with HoltWinters?

  • 2
    $\begingroup$ Do you expect a moving average to project a trend? If so, please see Wikipedia's remark "Simple exponential smoothing does not do well when there is a trend in the data" and the subsequent passages. $\endgroup$
    – whuber
    Dec 9, 2019 at 14:58
  • 2
    $\begingroup$ Thanks. I introduce the trend component with beta factor in HoltWinters function: tsRedditoMedioForecast <- HoltWinters(redditoMedio, beta=TRUE, gamma=FALSE) And now I have my prediction line $\endgroup$
    – wikimt
    Dec 9, 2019 at 15:14

1 Answer 1


I put the trend component in my model and it works! Thansk whuber

tsRedditoMedioForecast <- HoltWinters(redditoMedio, beta=TRUE, gamma=FALSE) 

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