How to Make a Comparison Chart in Looker with AI

Building comparison charts is one of the most effective ways to understand your business performance, but getting it right in Looker Studio (formerly Google Data Studio) can feel like a chore. This guide walks you through the step-by-step process of creating powerful comparison charts and shows you how AI is changing the game by turning hours of clicks into simple conversations.

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Why Bother with Comparison Charts?

Before jumping into the how-to, let's quickly cover the why. Comparison charts transform raw data into clear stories. They help you answer critical business questions at a glance, such as:

• Is our website traffic growing month-over-month?
• Which of my new ad campaigns is outperforming the others?
• How does sales performance this quarter stack up against the same quarter last year?
• Are Facebook Ads or Google Ads driving a better return on investment?

By placing data points side-by-side, you can immediately spot trends, identify outliers, and make informed decisions instead of relying on gut feelings. They are the foundation of effective performance analysis.

Building a Comparison Chart in Looker Studio: The Manual Method

Looker Studio is a powerful free tool, but it requires a hands-on approach. Let's build a classic month-over-month traffic comparison chart using a Google Analytics data source.

Step 1: Set Up Your Report and Chart

First, open a new or existing report in Looker Studio. If you haven't already, add your data source (in this case, Google Analytics).

Once your canvas is ready:

1. Navigate to the toolbar and click Add a chart.
2. Select a Time series chart from the dropdown menu. Time series charts are perfect for comparing performance over different periods.
3. Place the chart on your report canvas. Looker Studio will automatically populate it with some default data from your source.

Step 2: Configure Your Dimensions and Metrics

With your chart selected, the Properties panel will appear on the right side of the screen. This is where you tell the chart what data to show. Under the Setup tab:

• Dimension: Set the primary dimension to Date. This is the "when" of your data, plotted along the x-axis.
• Metric: Add the metric you want to measure, such as Sessions or Total Users. This is the "what," plotted along the y-axis.

Right now, your chart shows your sessions over your selected date range. It’s useful, but it lacks comparison. Let’s change that.

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Step 3: Add a Comparison Date Range

This is where the magic happens. A little further down in the Setup panel, you'll find the Default date range section. This is the key to time-based comparisons.

1. Find the Comparison date range option. Click on it.
2. A menu will appear with several options. To compare your current period to the one immediately preceding it, select Previous period. For a year-over-year comparison, you would choose Previous year.
3. Click Apply.

Your time series chart will instantly update. You’ll now see two lines: one for the current period (e.g., this month) and one for the previous period (e.g., last month). Looker Studio also adds helpful summary scorecards telling you the percentage change. You've just created a month-over-month comparison chart!

More Advanced Comparison Scenarios

Time-based comparisons are common, but what about comparing categories, like marketing channels or ad campaigns? This often requires a bit more wrangling.

Example 1: Comparing Campaign Performance

Let's say you want to see which of your Google Ads campaigns is bringing in the most revenue. For this, a Bar chart is a better choice.

• Add a Bar chart to your report.
• Set the Dimension to Campaign.
• Set the Metric to Total Conversions or a revenue metric.

The chart will rank your campaigns, making it easy to see the top performers. To compare against another metric, like Cost, simply add Cost as a second metric. Looker will then display bars for both revenue and cost for each campaign.

Example 2: Comparing Different Data Sources (The Hard Part)

What if you want to compare performance across platforms, like Facebook Ads revenue vs. Google Ads revenue? Since this data lives in separate sources, a simple chart won't work. You’ll need to use Looker Studio’s Blend Data tool.

Blending data involves:

1. Adding your first data source (e.g., Google Ads).
2. Clicking the Blend Data option in the properties panel.
3. Adding your second data source (e.g., your Facebook Ads data, which you likely have in a Google Sheet).
4. Configuring the "join key" - a shared dimension that links the two sources, like Date or Campaign.
5. Defining the dimensions and metrics from each source that you want to appear in the blended chart.

This process is powerful but can be confusing and error-prone. If your join keys don't match up perfectly, your data will be incorrect. It’s one of the biggest hurdles for marketers who just want a simple, unified view of their performance.

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Simplifying Comparison Charts with AI

The manual method in Looker Studio works, but it's slow. It forces you to think like a report builder - clicking, dragging, configuring panels, and debugging data blends. Every question you have requires a sequence of technical steps to answer. This is where AI-driven analytics tools flip the script entirely.

Imagine if, instead of clicking through endless setup panels, you could just ask for what you want?

From Manual Clicks to Natural Language

New AI analytics platforms eliminate the technical barriers. They connect directly to your data sources - Google Analytics, Facebook Ads, Shopify, HubSpot, etc. - and let you build reports using plain English.

Instead of manually creating that month-over-month traffic report, you could simply type a prompt like:

“Show me sessions from last month compared to the previous month as a line chart.”

The AI understands the request, pulls the correct data from your connected Google Analytics account, configures the chart, sets the comparison date range automatically, and presents you with the finished visualization in seconds.

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Asking More Complex Questions with Ease

The real power of AI emerges when you tackle more complex comparisons that would require data blending or calculated fields in Looker Studio.

Consider the task of comparing Facebook Ads and Google Ads. Instead of wrestling with the data blender, you could ask:

“Create a bar chart comparing spend versus revenue for my Facebook Ads and Google Ads campaigns this quarter.”

The AI handles everything in the background. It knows where your Facebook data lives and where the Google data lives, understands how to join them, calculates your totals for each, and builds the chart exactly as you asked. This removes the entire layer of technical busywork, allowing you to move straight from question to insight.

This approach isn’t about just getting charts faster, it's about enabling a deeper, more fluid conversation with your data. You can ask a question, see the result, and immediately ask a follow-up, like:

“Okay, which of those campaigns had the best ROI?”

And you get an instant answer, without having to build a new view or find the right formula for a calculated field. This makes data analysis accessible to everyone on the team, not just the data expert.

Final Thoughts

Building comparison charts is fundamental to smart decision-making, and Looker Studio offers a robust (if manual) way to do so. By mastering dimensions, metrics, and comparison date ranges, you can analyze your performance effectively. However, the path to clear insights is often filled with tedious clicks, complex configurations, and frustrating data-blending issues.

This is precisely the problem we built Graphed to solve. We believe getting answers from your data shouldn't require you to become a BI tool expert. By connecting all your marketing and sales platforms in one place, we enable you to create real-time dashboards and reports simply by asking questions in plain English. There’s no complex setup or steep learning curve - just connect your sources and get back to growing your business while AI handles the reporting grunt work.