“Compare to Past” is a powerful tool which allows users to directly compare a current period of operation to some time in the past. This is different from the Baseline model in that there are no calculations, weather-adjustments, or assumptions; the data shown is exactly as it was recorded and shown in the past.
Example: A user wants to verify if their morning startup time following a long weekend is too long. There are usually not enough long weekends, or holidays, in a year for the Baseline model to accurately predict what will happen around those weekends, so direct comparisons can be a better tool.
- Navigate to Explorer and open the period of time you wish to compare against the past. Click the “Compare to Past” button near the top-left of the graph.
- This will open a date picker with two pre-filled options and a calendar to manually choose a period of time.
- Previous Period: This compares against the previous “chunk” of time equal to the current “chunk” we are viewing. If we are looking at the past 7-days, “Previous Period” will show us the 7-days immediately preceding, starting 14-days ago.
- Last Year: This compares against the same days from the previous year, with the timing slightly adjusted so the weekdays and weekends match up.
- Since we want to compare against a 3-day weekend from last year, we will select “Last Year.” The calendar will automatically update to show us the dates we will be comparing against.
- Users can adjust this date range by clicking on the calendar to select a custom date range instead, the date range will automatically update. There are no restrictions on this, so we recommend picking the same weekday to start as the current data (e.g. if your date range starts on a Tuesday, pick a Tuesday to start the comparison range).
- Select “Apply” when finished selecting dates.
- The historic data will show up as a dotted line, and information about both current and historic data sets can be seen by mousing over the graph. Information is also displayed below the graph in table format.
- Any data points in Explorer can be toggled on and off to view current and historical data; these will each show current data as a solid line and historical as a dotted line.
- This can get busy quickly, but historic or current data can be toggled on/off quickly from the legend at the bottom of the chart.
Items of Note for Compare to Past
- Compare to past data can be exported into csv format from Explorer, like any other data set, by clicking on the three dots at the top right of the chart and selecting “Download csv”.
- Compare to past works best when the current date range extends over complete 24-hour periods, typically when the current date range is the default or is chosen from the date picker calendar. We do not recommend trying to compare to past on a selection where a user has used the click and drag to zoom functionality, as compare to past may not function properly.
- Sending or copying a link from your browser when viewing compare to past will not carry over the comparison, instead it will show the current data over the current date range, and the compare-to-past will have to be done again.
- Historical data typically takes longer to load than more current data, so users may need to wait slightly longer for the compare to past data to appear on the chart in Explorer.