Dimensions vs. Measures & Continuous vs. Discrete

About the roles and types of data fields

This article contains a video tutorial and written steps about Dimensions vs. Measures & Continuous vs. Discrete in Tableau, how to build specific types of charts and how to use them in your day-to-day reporting activity.

Data fields are created from columns in your data source. Each field is automatically assigned a data type (such as integer, string, date) and a role: Discrete size or Continuous measure (more common), or Continuous size or Discrete measure (less common).

Dimensions contain qualitative values (such as names, dates, or geographic data). You can use parameters to classify, segment, and reveal details in your data. Dimensions affect the level of detail in your view.

Measurements contain numerical, quantitative values that you can measure. Measures can be aggregated. When you drag a measure into the view, Tableau applies an aggregation to that measure (by default).

Tableau represents data differently in visualization, depending on the type of discrete (blue) or continuous (green) field. Continuous and discreet are mathematical terms. Continuous means “the formation of an uninterrupted, uninterrupted whole”; discrete means “separate and distinct individual.”

Measures in green, or dimensions are continuous. Continuous field values are treated as an infinite range. In general, continuous fields add axes to the view.

Measures in blue when the dimensions are also set as discrete and they are discreet. Discrete values are treated as finite. In general, discrete fields add headers to the view.

Examples of continuous and discrete fields used in a view

In the line chart example, the Quantity field is set to Continuous, which creates a horizontal axis at the bottom of the view. The green background and the axis help you see that it is a continuous field.

In the bar chart example, the Quantity field has been set to Discrete. It creates horizontal headers instead of an axis. The blue background and horizontal headers help you see that it is discreet.

In both examples, the Sales field is set continuously. It creates a vertical axis because it is continuous and has been added to Rows. If it were on columns, it would create a horizontal axis. The green background and the aggregation function (in this case, SUM) help to indicate that it is a measure. The absence of an aggregation function in the name of the Quantity field helps to indicate that it is a dimension.

Size fields in the view

When you drag a discrete-sized field into Rows or Columns, Tableau creates column or row headers.

In many cases, the fields in the Size area will be initially unobtrusive when you add them to a view with a blue background. The given dimensions and numerical dimensions can be discrete or continuous, and all measures can be discrete or continuous, for which we will draw ”Category” one by one. After dragging a dimension in rows or Columns, you can change the field to a certain extent just by clicking on the field and choosing Measure and we will choose distinct count. Now the view will contain a continuous axis instead of column or row headers, and the background of the field will turn green:

Date dimensions can be discrete or continuous. Dimensions containing strings or Boolean values cannot be continuous. The picture does not add up.

How size affects the level of detail in the view

The level of detail in a view refers to how granular the size and measurement data in the view is. As you add dimensions to Rows or Columns, the number of marks in the view increases.

To understand why adding dimensions increases the number of marks in the view, do the following:

We will drag the Segment into Columns.

The status bar at the bottom of the Tableau window shows you that there are now three bookmarks in view.

These signs contain only substitute text, Abc, because you are only building the view structure at this time.

We’ll pull the Region to the Columns. Now there are 12 marks. We will add ship data to the rows and now the total is 56 marks. We could continue to add dimensions to Rows and Columns and notice that the total number of marks continues to grow. Dragging a size to a location on the Marks card, such as Color or Size, will also increase the number of marks, although it will not increase the number of titles in the view.

The process of adding dimensions to the view to increase the number of signs is known as setting the level of detail. Adding a dimension to pages/filter / columns/rows and marks in Tableau affects the level of detail:

The view now contains 56 separate instances of Abc – the view is complete and has no content. We will correct this by dragging Sales into Text. The table can now be considered complete:

Measures into the view

When you drag a measure into the view, it is aggregated by default. The type of aggregation will vary depending on the type of view. You should always check the aggregation and modify it if necessary. When you drag a continuous field from the Data in Rows or Columns panel, Tableau creates a continuous axis for that field.

If you click the field and change it to Discrete, the values become header headers.

Tableau aggregate default

Tableau continues to add values for the field because, although the field is now discrete, it is still a measure, and Tableau aggregates the measures by default. In cases where Tableau misclassified a field as size or size, possibly due to the type of data, you can convert it and change its role. If a measure contains numbers that do not need to be aggregated (such as a field that contains date values), we recommend turning it into a dimension.

Filter

When you place a data field on the filter, the result can be a discrete filter or a continuous filter. (add category). When you place a continuous measure (sales) on Filters, Tableau first asks you to choose a filter aggregation and then asks you to specify how to filter the continuous range of values.

Discrete versus continuous colour fields

When you place a discrete field on Color in the Marks card, Tableau displays a categorical palette and assigns a colour to each value in the field.

When you place a continuous field on Color, Tableau displays a quantitative legend with a continuous range of colours.

Watch the video tutorial here: