what is the holt winter method what is the holt method i used to find seasonality what is the difference in dshw and r holt seasonality what model to use in r for seasonality what is holt seasonal why does dshw show null values what is the difference between dshw and holt method why does the holt method fail when i test r does dshw show sse why do I get null seasonality can i use double seasonal holt winter model in r when dshw returns null what does dshw mean dshw double season holt method of seasonality what is seasonal holt method holt winter method why do i have to use dshw in r can a seasonal model be used in holt what model does holt use