Trend Lines – How to Add Line of Best Fit in Google Sheets

Visualizing data through charts and graphs is a powerful way to understand the relationships between variables. Adding a trend line, also known as the line of best fit, to your chart can offer valuable insights into your data. In this tutorial, we will explore how to add a line of best fit in Google Sheets to enhance your data analysis.

What is a Line of Best Fit and Why Add a Trendline?

A trend line, or a “line of best fit,” is a line superimposed on a chart to identify trends within the data. By adding this line, you can better understand the direction of the data, make forecasts, and observe relationships between data elements.

For example, let’s consider a scatter chart. Without a trend line, it may be challenging to determine if there’s an upward or downward trend. Adding a trend line provides clarity, allowing you to comprehend the data distribution, identify outliers, and make predictions about future data points.

Trend lines can be added to various chart types, including bar, line, column, or scatter charts. In the following sections, we will focus on adding a trendline to a scatter chart in Google Sheets.

How to Add a Line of Best Fit in Google Sheets

Before we dive into adding a line of best fit, let’s quickly review how to create a scatter chart using the data below:

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The data consists of the number of times ads were posted and the corresponding number of sales made. To visualize this data effectively, a scatter chart is an excellent choice. Here’s how to create a scatter chart in Google Sheets:

Creating a Scatter Chart in Google Sheets

1. Select the data range, including the column headers (e.g., A1:B22).
2. Click on the “Insert” menu from the menu bar.
3. Choose the “Chart” option.
4. The chart editor will appear, displaying a chart on the worksheet and a Chart Editor sidebar on the right side of the window.

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5. If Google suggests a different chart type, proceed to step 6. Otherwise, you can stop here.
6. To convert the displayed chart to a scatter chart, select the “Setup” tab in the Chart Editor.
7. Under the “Chart Type” dropdown menu, choose “Scatter Chart” from the suggested or other category.

Now you should have a scatter chart on your worksheet. Let’s proceed to add a line of best fit to gain a deeper understanding of the trends in your data.

How to Find the Line of Best Fit in Google Sheets

Google Sheets doesn’t require you to use a specific equation for the line of best fit. Instead, you can make customizations to the chart. Here’s how to add a line of best fit to the scatter chart we created:

1. Click on the “Customize” tab in the Chart Editor.
2. Select the dropdown menu for “Series.”
3. Scroll down and select the “Trend line” checkbox.

This action will display a trend line (or line of best fit) across your scatter chart. In our example, you’ll notice an upward trend in the chart, indicating that as the number of ads increases, sales also increase.

Making Changes to the Trend Line

If you want further customization of the trend line, you have various options available. Under the trend line checkbox, you can:

1. Change the type of trend line, like linear, exponential, polynomial, logarithmic, power series, or moving average.
2. Modify the line color.
3. Adjust the opacity and thickness of the trend line.
4. Change the label for the trend line.
5. Display the R2 value, which indicates how closely the trend line fits the data (the closer to 1, the better the fit).

For polynomial trend lines, you can also select the polynomial degree. Similarly, for moving average trend lines, you can choose between trailing or centered averages and select the number of periods.

Feel free to experiment with these different options until you find a trend line that provides valuable insights into your data.

Adding Multiple Trendlines in Google Sheets

If your scatter chart contains multiple series, you can add a trendline for each set of data. Let’s look at an example:

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Suppose we want trendlines for both Product A and Product B. Here’s how you can achieve that:

1. Navigate to “Chart editor > Customize > Series.”
2. Ensure that the drop-down list has “Apply to all series” selected.
3. Check the “Trendline” box.

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Alternatively, you can add trendlines to individual data sets by selecting the specific series from the dropdown menu instead of “Apply to all series.”

Using the TREND Function to Make a Trendline

While the TREND function is mainly used for forecasting future values, you can also utilize it as a trendline in Google Sheets. The syntax for this function is as follows:

=TREND(known_data_y, [known_data_x], [new_data_x])

To use the TREND function in your data set, you need to input the known y and x values and provide new x values for prediction based on the existing data. To make it work with current values, you can use the known x values as the new_data_x value.

For example, considering the following values:

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You can substitute the x and y values into the TREND function like this:

=TREND(B2:B8,A2:A8,A2:A8)

This will give you the following results:

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By charting the data, you can observe a clear trend that the trendline represents.

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Please note that using the TREND function to build a line of best fit in Google Sheets can be convoluted. We highly recommend utilizing it primarily for forecasting purposes.

How to Insert a Trendline in Google Sheets: FAQs

Does Google Sheets Have a Line of Best Fit?

Yes, Google Sheets refers to the line of best fit as a trendline.

How Do You Add a Line of Best Fit in Google Sheets?

To add a trendline in Google Sheets, follow these steps:

1. Open the Chart editor and go to Customize.
2. In the Series tab, check the box labeled “Trendline.”

Is a Trendline the Same as a Line of Best Fit?

Yes, in the context of Google Sheets, a trendline and a line of best fit are equivalent.

Where Can I Find R2 in Google Sheets? How Can I Determine the Slope of a Line of Best Fit in Google Sheets?

Finding the slope of a line of best fit in Google Sheets is straightforward:

1. Go to “Chart editor > Customize > Series.”
2. Ensure that the “Trendline” checkbox is selected.
3. To display the slope equation, change the “Label” to “Use equation.”
4. To show the R2 slope, check the “R2” box.

Which Equation Should I Use from the Types Menu?

The equation you select from the Types dropdown menu affects the shape of the line of best fit in Google Sheets. Here’s a brief explanation of each option:

• Linear: Creates a straight line of best fit from the data points.
• Exponential: Indicates an increasing or decreasing rate from the initial data point.
• Logarithmic: Represents a rapidly increasing or decreasing set of data that flattens out over time.
• Polynomial: Suitable for varied data.
• Power series: Reflects a steady increase or decrease from the initial value.
• Moving average: Smooths out volatile data.

Please note that there is no bell curve option available.

Wrapping Up the Line of Best Fit Tutorial

In this tutorial, we have explored how to add a line of best fit in Google Sheets to enhance your data analysis. The line of best fit, or trendline, enables you to observe trends, understand data point relationships, and identify outliers that may have been difficult to detect otherwise.

I hope this tutorial has been helpful. For more Google Sheets tutorials, visit Mr Reviews.