3. Fitting a regression model of the series on a periodic function (e.g. sine wave of a fixed period) of the time index and subtracting off the fitted model from the series. What could this method...

Consider the following techniques of transforming time series data. Choose all that apply

Extracted text: 3. Fitting a regression model of the series on a periodic function (e.g. sine wave of a fixed period) of the time index and subtracting off the fitted model from the series. What could this method achieve? (Choose all that apply.) remove a linear trend remove a nonlinear trend remove increasing variance remove seasonal variation 4. Differencing the data one or more times. What could this method achieve? (Choose all that apply.) remove a linear trend remove a nonlinear trend remove increasing variance remove seasonal variation