Combo charts in Excel - Deep Dive

Overview - Combo charts

What is it?

A combo chart in Excel is a single chart that combines two or more chart types, such as a column chart and a line chart, to display different types of data together. It helps show relationships between different data sets that have different scales or formats. For example, you can show sales numbers as columns and profit margin as a line on the same chart. This makes complex data easier to understand at a glance.

Why it matters

Combo charts solve the problem of comparing different types of data that don’t fit well on the same scale or chart type. Without combo charts, you might need multiple charts or struggle to see how different data relate. This wastes time and can confuse decision-makers. Combo charts make reports clearer and faster to interpret, helping businesses and individuals make better choices.

Where it fits

Before learning combo charts, you should understand basic chart creation in Excel, like making column and line charts. After mastering combo charts, you can explore advanced chart customization, dynamic charts with formulas, and dashboard design to present data interactively.

Mental Model

Core Idea

A combo chart blends different chart types in one view to compare diverse data clearly and effectively.

Think of it like...

Imagine a fruit salad where each fruit represents a different flavor and texture. Just like mixing apples and bananas creates a tasty mix, combining chart types mixes data styles to make a clearer picture.

┌─────────────────────────────┐
│        Combo Chart          │
├─────────────┬───────────────┤
│ Column Chart│ Line Chart    │
│ (Sales)    │ (Profit Margin)│
└─────────────┴───────────────┘

Build-Up - 7 Steps

1

Foundation

Understanding Basic Chart Types

Concept: Learn what column and line charts are and when to use them.

A column chart shows data as vertical bars, good for comparing amounts. A line chart connects points with a line, great for showing trends over time. Both are simple ways to visualize numbers but serve different purposes.

Result

You can create simple column and line charts from data in Excel.

Knowing basic chart types helps you understand why combining them can show more information clearly.

2

Foundation

Creating a Simple Chart in Excel

Concept: Learn how to select data and insert a basic chart.

Select your data range, go to the Insert tab, and choose a chart type like Column or Line. Excel will create a chart based on your selection. You can move and resize the chart on the sheet.

Result

A chart appears on your worksheet showing your selected data visually.

Mastering chart creation is essential before combining charts, as combo charts build on these basics.

3

Intermediate

Introducing Combo Charts

🤔Before reading on: do you think combo charts are just two charts placed side by side or a single chart combining types? Commit to your answer.

Concept: Combo charts combine two or more chart types into one chart area.

In Excel, you can create a combo chart by selecting your data, then choosing Insert > Combo Chart. You pick which data series uses which chart type, like columns for one series and a line for another. This lets you compare different data styles together.

Result

A single chart shows multiple data series with different chart types, making comparisons easier.

Understanding that combo charts merge chart types in one view unlocks more powerful data storytelling.

4

Intermediate

Setting Different Axes for Data Series

🤔Before reading on: do you think all data series in a combo chart must share the same vertical axis? Commit to your answer.

Concept: Combo charts can use primary and secondary vertical axes to handle different data scales.

When data series have very different ranges (like sales in thousands and percentages), Excel lets you assign one series to the primary axis and another to the secondary axis. This way, both series fit well visually without distorting the data.

Result

The combo chart shows two vertical axes, each scaled for its data series, improving clarity.

Knowing how to use dual axes prevents misleading charts and helps show true relationships between data.

5

Intermediate

Customizing Combo Chart Types per Series

Concept: Learn to assign specific chart types to each data series in a combo chart.

In the combo chart dialog, you can pick a chart type for each data series individually. For example, set sales as clustered columns and profit margin as a line. This customization highlights different data characteristics effectively.

Result

Each data series displays in the chosen chart style within the same chart area.

Customizing chart types per series lets you tailor the visual story to your data’s nature.

6

Advanced

Using Combo Charts for Complex Data Stories

🤔Before reading on: do you think combo charts can only show two data series or more? Commit to your answer.

Concept: Combo charts can combine multiple chart types and series to tell complex data stories.

You can add more than two data series, each with its own chart type and axis if needed. For example, sales as columns, profit margin as a line, and units sold as an area chart. This layered approach helps analyze multiple factors in one view.

Result

A multi-series combo chart displays diverse data types clearly and interactively.

Understanding combo charts’ flexibility allows you to create rich, insightful visualizations beyond simple comparisons.

7

Expert

Avoiding Misleading Visuals in Combo Charts

🤔Before reading on: do you think using different axes in combo charts can confuse viewers or clarify data? Commit to your answer.

Concept: Expert use of combo charts requires careful axis scaling and labeling to avoid misinterpretation.

If axes are not clearly labeled or scaled properly, combo charts can mislead viewers by exaggerating or hiding trends. Experts ensure axis titles, consistent scales, and clear legends to maintain honesty and clarity in data presentation.

Result

Combo charts communicate data truthfully and effectively without confusing the audience.

Knowing how to design combo charts responsibly prevents common pitfalls that reduce trust in data.

Under the Hood

Excel stores data series separately and renders each using the specified chart type within the same chart area. It manages multiple vertical axes by scaling each axis independently based on the assigned data series range. The chart engine overlays these visual elements, aligning them horizontally by category labels to create a unified view.

Why designed this way?

Combo charts were designed to solve the problem of visualizing data sets with different units or scales together. Instead of forcing all data into one chart type or scale, combining chart types and axes allows clearer comparisons. This design balances flexibility with clarity, avoiding clutter from multiple separate charts.

┌───────────────────────────────┐
│          Combo Chart           │
│ ┌───────────────┐ ┌─────────┐ │
│ │ Data Series 1 │ │ Axis 1  │ │
│ │ (Column)     │ │ (Sales) │ │
│ └───────────────┘ └─────────┘ │
│ ┌───────────────┐ ┌─────────┐ │
│ │ Data Series 2 │ │ Axis 2  │ │
│ │ (Line)       │ │ (Margin)│ │
│ └───────────────┘ └─────────┘ │
└───────────────────────────────┘

Myth Busters - 4 Common Misconceptions

Quick: Do combo charts always require a secondary axis? Commit to yes or no.

Common Belief: Combo charts must always use a secondary axis for one of the data series.

Reality: Combo charts can use a single axis if the data series share a similar scale; a secondary axis is optional.

Why it matters: Using a secondary axis unnecessarily can confuse viewers and complicate the chart without benefit.

Quick: Can you mix any chart types in a combo chart? Commit to yes or no.

Common Belief: You can combine any chart types freely in a combo chart without restrictions.

Reality: Not all chart types combine well; some, like pie charts, cannot be part of a combo chart in Excel.

Why it matters: Trying to combine incompatible chart types wastes time and leads to errors or poor visuals.

Quick: Does changing one series chart type in a combo chart affect others? Commit to yes or no.

Common Belief: Changing the chart type of one data series automatically changes all others to match.

Reality: Each data series in a combo chart can have its own independent chart type without affecting others.

Why it matters: Misunderstanding this limits creativity and prevents effective use of combo charts.

Quick: Do combo charts always make data easier to understand? Commit to yes or no.

Common Belief: Combo charts always improve data clarity by combining chart types.

Reality: Poorly designed combo charts with unclear axes or too many series can confuse viewers.

Why it matters: Assuming combo charts are always better can lead to misleading or cluttered visuals.

Expert Zone

1

Assigning the correct axis to each series is crucial; mismatched axes can distort data interpretation.

2

Using transparent fills or subtle colors helps distinguish overlapping chart types without clutter.

3

Dynamic combo charts can be created using named ranges and formulas to update automatically with data changes.

When NOT to use

Avoid combo charts when data series are too numerous or complex, as the chart can become cluttered. Instead, use separate focused charts or interactive dashboards with filters to explore data clearly.

Production Patterns

Professionals use combo charts in financial reports to show revenue (columns) and profit margin (line) together. They also appear in marketing dashboards combining campaign spend and conversion rates. Experts customize axes, colors, and labels carefully to maintain clarity.

Connections

Data Visualization Principles

Combo charts apply core visualization principles like clarity and comparison by combining visual encodings.

Understanding visualization principles helps design combo charts that communicate data truthfully and effectively.

Dashboard Design

Combo charts are key components in dashboards, enabling compact display of multiple data types.

Knowing how combo charts fit in dashboards helps create interactive and insightful reports.

Multimodal Communication

Combo charts use multiple visual modes (bars, lines) simultaneously, similar to how multimodal communication uses different channels to convey messages.

Recognizing combo charts as multimodal tools highlights the power of combining formats to enhance understanding.

Common Pitfalls

#1 Using a secondary axis without labeling it clearly.

Wrong approach:

Created a combo chart with two axes but left the secondary axis unlabeled.

Correct approach:

Created a combo chart and added a clear title and units label to the secondary axis.

Root cause:

Assuming viewers will understand the meaning of the secondary axis without explicit labels.

#2 Combining too many data series in one combo chart.

Wrong approach:

Added five different data series with different chart types and axes, making the chart cluttered.

Correct approach:

Limited the combo chart to two or three series and used separate charts or filters for additional data.

Root cause:

Believing more data in one chart always improves insight, ignoring visual overload.

#3 Assigning incompatible chart types in a combo chart.

Wrong approach:

Tried to combine a pie chart with a column chart in a combo chart.

Correct approach:

Used column and line charts together, which Excel supports in combo charts.

Root cause:

Not knowing Excel’s combo chart limitations and chart type compatibility.

Key Takeaways

Combo charts let you combine different chart types in one view to compare diverse data clearly.

Using primary and secondary axes helps display data series with different scales without distortion.

Customizing each data series’ chart type allows you to highlight unique data characteristics effectively.

Poorly designed combo charts can confuse viewers, so clear labeling and thoughtful design are essential.

Combo charts are powerful tools in dashboards and reports but should be used thoughtfully to avoid clutter.