Option A: Building a line chart manually, with drag-and-drop
- Drag “ISO time” to Columns or top of view area
The default aggregation when you do this should be "Year(ISO time)" in blue, as shown below. If you get something else, just use the arrow on the right of the ISO time bubble and find the first "Year" in the drop down.
- Drag “Number of Records” to Rows or left of view area
Limit to last 20 years
- Drag “ISO time” to Filters
- Click “Relative dates”
- Select “Years”
- Click the button for “Last”
- Adjust to 20 years
Option B: Create a line chart with Show Me
- Click “ISO time”
The default aggregation when you do this should be "Year(ISO time)" in green, as shown below. If you get something else, just use the arrow on the right of the ISO time bubble and find the second "Year" in the drop down.
- Ctrl-click “Number of Records”
- Open Show Me
- Select line chart
Why are the two charts so different?
- One has “Year(ISO time)” in green, while the other has it in blue.
- In the data window, “ISO time” is blue, which means “discrete.”
A discrete variable is like a category; values may have an order, but there isn’t anything in between them.
- Line charts normally use a “continuous” date, though, so Show Me converted “ISO time” to green.
A continuous variable is like the full number range; you may only have a few values, but there are more possible numbers in between them.
- If you click the "+" sign to expand the Year variables in each chart, they will both disaggregate down to the Quarter level. The "discrete" chart, however, will treat quarters as categories, whereas the "continuous" chart will just add more points to the line.
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