what does the difference in a time series mean stationarity in time series definition do i need to detrend a time series does the time series change stationarity if i take out trend and seasonality does it mean we are left with only irregularity on which we plot the acf and pacf to arrive at the MA and AR order? how to calculate stationarity in a time series how is stationarity different between time-series time series stationarity definition excel do you have to detrend first and second time series difference between a time and series does 1st difference and 2nd difference mean the same thing what would it mean when we take out trend and seasonality how to plot seasonality for stationarity time series stationarity difference between seasonality and time series difference difference stationarity when i take out trend and seasonality do we still have irregularity when you difference a time series and take out trend and seasonality difference and second difference definition in statistics what is stationarity of time series