Consider the following chart.

The word "series" is used to describe something unique about the data such as the city.

There is also something common to each series curve such as the month represented on the X axis. While this example used time as the basis of the X axis, another chart could have used something else such as elevation.

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Another chart might look like the following. For this one, the year is the series, and the country is the X axis (and country isn't even on the X axis for a bar chart but only a column chart so using that name isn't good!).

enter image description here

For this one, the series is the person, and the x-axis is the fruit.

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For this one, the series is also the person, and the x-axis is the fruit.

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I am designing an application were the user can add a new series as well as a new X axis point. I am thinking of two buttons Add New Series and Add New X Axis.

I am thinking the user workflow will be as follows:

  1. User adds a new empty chart by selecting the type of chart they wish to add (i.e. line, pie, bar, etc) and giving it a name.
  2. User adds a series and gives it a name.
  3. User adds what I refer as the x-axis point and gives it a name. I think it will initially be added with an empty value (more on this later).
  4. User clicks the empty point, and can add a value.
  5. User repeats step 3 (and optionally step 4), and adds two more x-axis points.
  6. User adds another series. That series automatically has empty values for the three x-axis points.
  7. User deletes an x-axis, and the values are removed from the three series.
  8. User changes the chart type if they want.

Using Excel as a design pattern, I can create the following charts using the same data. For this, I called the independent variable "row". While this makes sense from the spreadsheet prospective, it doesn't make sense from most of the chart's perspective. What would a user think if there was an "Add New Row" or "Delete Row" button?

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I feel the word "series" works (correct me if you feel differently), however, I don't know a good word to describe the x axis. The reason I am using x-axis is that the JavaScript library Highchart uses it.

What word should be used in place of x-axis?

  • Well, the x-axis is also known as the axis of abscissas while the y-axis is called the axis of ordinates. So you could say "Add new Abscissas". Leaving this as a comment not an answer because I don't think this would be the most user friendly choice.
    – DasBeasto
    Aug 2, 2016 at 18:23
  • 1
    Thanks DasBesto. You must be a mathematician! Yea, agree it isn't the most user friendly. Aug 2, 2016 at 18:26
  • I don't really like it, but maybe "Add Variable"? Aug 2, 2016 at 19:04
  • A "series" is typically defined as a set of data, being a list of pairs of values that are then plotted against X and Y axes. That being said, what do you intend by the ability "to add a new X axis point"?
    – TScott
    Aug 2, 2016 at 20:25
  • 1
    It sounds like your user will be adding a data point or data value (as an X-Y pair of values), not adding an "x axis point". Is this something the user will do in the chart, or in the related data somewhere else? And are they adding a new data value, or choosing to plot an additional already existing item? In other words, conceptually think of separating out the table of data that chart is drawn from, and the chart itself. Are they adding a new point to the table, or choosing more values to plot form the table that they didn't plot additionally?
    – TScott
    Aug 2, 2016 at 21:49

3 Answers 3


Who are the users?

It's a good question and well presented, but seeing as this is a UX Q&A site, it would really help (others and in turn you) to know who the users are?

Depending on their background and discipline, people may call it different names; dependent and independent variables even?

It's hard to give definite answer without some context on the users.

Distinguish axis from series

The word axis in this context denotes a reference line in a coordinate system. I believe that the terms x-axis and y-axis will be clear to most people who finished high-school.

Then, there's the data series, which is actually plotted on some coordinate system that involve axis.

I believe that using axis and series interchangeably won't scale and can lead to some trouble. From a user perspective, there will be actions clearly related to the axis, and others related to the data series. For instance:

  • Adding ticks to a data series is nonsense.
  • Setting the range of the axis is different from setting the range of the data series.

If one is to consult existing designs, you'll probably find some sense in how Apple approached this:

A screenshot of Apple's number application, showing different tabs for axis and series.

  • Thanks Izhaki, Users will be administration staff and building engineers. Purpose is to primarily display energy use. I don't know Apple chart software. How are they using the word "Axis"? Aug 2, 2016 at 23:07

I'd do what Excel does when it makes graphs.

It adds 'labels' as in 'Kind of Fruit' or 'Number of Fruit Consumed'.

"Add new series" and "Add New X Axis" make no sense at all to me.

Mathematically you are supposed to put the independent variable - say time, on the x axis and the dependent variable (the thing that changes with time) - say temperature, on the y axis.

  • Don't have too much experience with Excel charts, but I think it is a great idea to mimic if they have it right. Let me mess around with them. Yes, I agree the X axis is the variable. I am concerned that people assume the X axis is always the horizontal access. Aug 2, 2016 at 22:26
  • Please look at my Excel charts added to my original post. How would someone add or delete the chart content for a given row? Aug 2, 2016 at 23:40
  • How about labels of "x axis variable" and "y axis variable" or "x axis data" and "y axis data" ?
    – PhillipW
    Aug 3, 2016 at 7:17
  • Humm. I think I might go with "Category". Series and Categories... Aug 3, 2016 at 15:23
  • At this point I'd suggest some quick user research: go around your office and ask people which terms mean the most to them.
    – PhillipW
    Aug 3, 2016 at 18:23

First, it looks like your app is limited to linear data? I.e., the user provides values that plot against the y-axis. (The corresponding x-axis values are assumed, starting at 0 and increasing sequentially by one.) Or, for example:

series : [
        values : [35,42,67,89,25,34,67,85]

is the same as:

series : [
        values : [

The reason I ask is that I agree with Izhaki. The series needs to be differentiated from the axes. They are two separate things. By "series", you're referring to the data, or the numbers contained in your spreadsheet. These values are plotted against the scales (the x- and y-axes). The text that appears on the x-axis would be referred to as scale items or scale labels. For a breakdown on the different scale elements, you can check out this X/Y-Axis Scales Tour.

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