My empty cells get displayed as zeros in tooltips
Sometimes, datasets have holes in them - for example in this chart below, some data are missing. Datawrapper automatically detects empty cells and assigns null-values. These will simply not be charted so usually there's no need to worry about them - however, sometimes they appear in tooltips as "0"s which can be misleading. In this tutorial, we'll talk about a workaround so that holes in your data are represented more accurately:
Notice the "0"s in the tooltips for iPad when tracing along 2004 - 2010:
Empty cells are detected as null-values:
Empty cells and null-values do not always equal zeros and this can be misleading. How do we fix this?
In order to make sure that zeros are not displayed in tooltips, what you can do is to replace the null values with " N/A" which basically means "no value available". The easiest way to do this is to do this in your original dataset. See the second sheet of this Google sheet, where all the empty cells have been replaced by N/A.
Then reimport the dataset by going back to Step 1: Upload data. When you proceed to Step 2: Check & Describe, now you'll see the color of cells changed to blue. This means Datawrapper correctly recognizes the N/A cells.
Now, the chart should no longer display tooltips with "0"s where there are not supposed to be!
If you're curious about learning more about null and zeros, you might find this video on "The Design of Nothing: Null, Zero, Blank" interesting.