I have a time series dataset with 200 data points. I have decomposed it using the function below:
dat2 = ts(dat1, frequency = 4) decomposeDat = decompose(dat2, "multiplicative")
I get 4 components: trend, seasonal, cyclic and irregularity. But when I check if there is seasonality present in the dataset with frequency "4", Rstudio says that there is no seasonality for this frequency. The check is performed with the following code:
dat2 = ts(dat1, frequency = 4) fit <- tbats(dat2) seasonal <- !is.null(fit$seasonal) seasonal
seasonal returns FALSE meaning that there is no seasonality with frequency 4.
Can someone explain, why can I decompose it into a seasonality component when no seasonality is present from the check mentioned above?