CODEWITHSUNDEEP
rtime-series
Programmerinthemaking
Programmerinthemaking

Reputation: 1

R : Help needed for linear regression in time series. The date column is of the format month-year

Time series Date Sales 1 Jan-95 1664.81 2 Feb-95 2397.53 3 Mar-95 2840.71 4 Apr-95 3547.29 5 May-95 3752.96 6 Jun-95 3714.74 7 Jul-95 4349.61 8 Aug-95 3566.34 9 Sep-95 5021.82

This is the time series code : t<-ts(data$Sales,frequency=12,start=c(1995,1))

This is the task I have to perform : Fit a linear trend model with additive seasonality (Model A) and exponential trend model with multiplicative seasonality (Model B). Consider January as the reference group for each model.

Upvotes: 0

Views: 70

Answers (1)

Mark
Mark

Reputation: 12548

As r2evans has said, it's difficult/impossible to solve conclusively without seeing the timeseries you created, as the frequency would determine the answer. But here is an answer which should work regardless of the frequency:

freq <- 12

# create a timeseries object
data <- ts(data = 1:1000, start = c(2010, 1), frequency = freq)

# seq() in this case creates a sequence of numbers from 1 to the length of the data, with a step of freq
data[seq(1, length(data), freq)]

Upvotes: 0

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