Trend lines in Tableau - Step-by-Step Guide

Introduction

Trend lines help you see patterns in your data over time or across categories. They draw a line through your data points to show the general direction or trend. This makes it easier to understand if values are going up, down, or staying steady.

When you want to see if sales are increasing or decreasing over months.

When you need to check if customer satisfaction scores improve with more service calls.

When you want to compare the trend of two products’ sales over a year.

When you want to predict future values based on past data patterns.

When you want to highlight the overall direction in a scatter plot of data points.

Steps

Step 1: Open your worksheet

- Tableau workspace

Your data visualization is visible on the screen

Step 2: Drag the dimension for time or categories to Columns or Rows

- Data pane

The chart updates to show data points over time or categories

Step 3: Drag the measure you want to analyze to Rows or Columns

- Data pane

A chart appears showing your data points

Step 4: Click the Analytics pane tab

- Left side panel

Analytics options appear

Step 5: Drag Trend Line into the view and drop it on the desired option (e.g., Linear)

- Analytics pane

A trend line appears on the chart showing the general data direction

💡 Use Linear for straight trends or Polynomial for curves

Step 6: Right-click the trend line and select 'Describe Trend Line'

- Chart area

A window opens showing details like slope and R-squared value

Before vs After

Before

Scatter plot shows many data points scattered without any line

After

Scatter plot shows a straight or curved line passing through data points indicating the trend

Settings Reference

Trend Line Model

📍 Analytics pane when dragging Trend Line

Choose the type of trend line that best fits your data pattern

Default: Linear

Show Confidence Bands

📍 Trend Line options after adding trend line

Display shaded area around the trend line to show prediction confidence

Default: On

Exclude Null Values

📍 Trend Line options menu

Decide whether to ignore missing data points when calculating the trend line

Default: Checked

Common Mistakes

Adding a trend line to a chart with too few data points

Trend lines need enough data points to show a meaningful pattern

Use trend lines only when you have enough data points, ideally more than 10

Choosing a linear trend line for clearly curved data

A linear line will not fit curved data well and can mislead interpretation

Select a polynomial or other curved model to better fit the data shape

Ignoring the R-squared value when interpreting the trend line

R-squared shows how well the trend line fits the data; ignoring it can lead to wrong conclusions

Check the R-squared value to understand the trend line’s accuracy

Summary

Trend lines show the general direction of your data over time or categories.

You add trend lines from the Analytics pane by dragging them onto your chart.

Choose the right model type and check the fit quality to get useful insights.