The moment you want distinct markers for two data sets, you are no longer just making a chart. You are making a decision about how your audience will read that chart, and that decision is worth more than a few clicks in a menu. The user asking about age bias plots for Reading 1 versus Reading 2 has hit on a universal truth: if your data points all look the same, your plot is not showing a comparison, it is showing a blur. Distinct shapes are not a cosmetic preference; they are the difference between a graph that whispers and one that states its case clearly.
This is not about flashy visuals or chasing an aesthetic ideal. It is about the quiet discipline of reducing friction for your reader. When you plot mean age against something else, and every point is a blue dot, you force your audience to do the work of remembering which dot belongs to which reading. That mental load adds up, and it distracts from the actual insight you are trying to deliver. By assigning a filled circle to Reading 1 and a cross to Reading 2, you are not just styling a plot. You are structuring an argument. You are telling your reader, "Here is the pattern, and here is how to see it without squinting."
The practical path is simpler than it feels. In most spreadsheet tools, you do not need a new chart type or a macro. You need to isolate the series. Select one set of points, open the formatting options, and change the marker to a shape that contrasts with the other set. A dot versus a cross, a triangle versus a square, an open circle versus a filled one. The goal is not to decorate but to differentiate. And once you do that, you will notice something else: your plot starts to communicate the relationship between the two readings with a clarity that was buried before. The eye moves faster, the comparison becomes instinctive, and the age bias you are trying to show stops hiding in plain sight.
So do not settle for generic blue dots because they are the default. Defaults are for convenience, not for communication. Take the extra minute to make your data points distinct, and you will find that your plot is no longer just a chart. It is a tool that respects your reader's attention and your own analytical intent. That is the kind of choice that separates a plot that merely exists from one that actually works.