Time as a grouping variable: column format-sensitive?
I want statistics (e.g. median, mean, etc.) on my data by various time intervals: day, week, month, year, etc. Two niggly questions: If I have a single time column, is the interval used for grouping sensitive to the column format? i.e. if the format to "m/y", does it group by months? If I then change the column format to "m/d/y", does it now group by days? If not, then I can certainly use the Day ...