What If Scenarios in Tableau

Building a dashboard that reports on past performance is useful, but what if you could use that same dashboard to predict the future? That’s the idea behind what-if scenario analysis, and Tableau makes it surprisingly easy to build this kind of interactive forecasting right into your reports. This article will show you how to use Tableau's parameters and calculated fields to let users explore potential outcomes and make better, data-informed decisions.

What Exactly is 'What-If' Analysis?

At its core, "what-if" analysis is a powerful way to see how changing one variable might impact other parts of your business. It allows you to move from reporting on what happened to exploring what could happen. Instead of just looking at last quarter's sales, you can ask dynamic questions right within your dashboard:

• What if we increase our marketing budget by 10% next quarter? How would that affect website traffic and new leads?
• What if our top-selling product's cost goes up by 5%? What's the impact on our overall profit margin?
• What if we manage to improve our sales team's conversion rate by 2%? How much additional revenue would that generate?

By building these scenarios into your Tableau dashboard, you transform it from a static report into an interactive exploration tool. It empowers team members and stakeholders to model different possibilities themselves, without needing to request a new report from an analyst for every question that pops into their heads.

The Building Blocks: Parameters and Calculated Fields

Tableau’s magic for what-if scenarios rests on two key features working together: Parameters and Calculated Fields. Understanding how they interact is the first step to building your own powerful models.

1. Parameters: The User's Controls

Think of a parameter as a variable that you, the report builder, create for your users to control. It's an input field – like a slider, a dropdown menu, or a text box – that isn’t part of your original data source. Users can change the value of the parameter, and that new value can then be used in your calculations and visualizations.

For a "what-if" scenario, a parameter might be "Projected Growth Rate," "Discount Percentage," or "Additional Marketing Spend." By adjusting this parameter, the user is an active participant in the analysis, providing the "what-if" number that drives the forecast.

2. Calculated Fields: Where the Math Happens

A calculated field is simply a new field (or column) that you create by applying a formula to your existing data. This is where you connect the user's input from the parameter to your actual data.

For example, if you have a [Sales] field and create a parameter called [Sales Uplift %], you can create a new calculated field named "Projected Sales" using a formula like this:

SUM([Sales]) * (1 + [Sales Uplift %])

This formula takes the original sales data and applies the percentage uplift chosen by the user in the parameter control. Every time the user changes the parameter’s value, Tableau recalculates this field, and every chart using it updates instantly.

Step-by-Step Guide: Building a Sales Forecast Scenario in Tableau

Let's walk through a common business example: forecasting sales. Imagine you're a sales manager wanting to visualize how a potential growth percentage would impact monthly sales figures. You want to provide a slider that lets other stakeholders see this impact in real time.

Step 1: Create the 'What-If' Parameter

First, we need to create the control that will let users input their assumed growth rate.

1. In your Tableau worksheet, right-click in the empty space of the Data pane (on the left side) and select "Create Parameter..."
2. The configuration window will open. Let's set it up:
3. Click OK. You'll now see your new parameter under the "Parameters" section in the Data pane.
4. To make it interactive, right-click on the Sales Growth Forecast % parameter and select "Show Parameter." The slider control will appear on your worksheet, typically on the right side.

Now you have an interactive slider, but it doesn't do anything yet. We need to connect it to our data using a calculated field.

Step 2: Create the Calculated Field

Next, we'll create the formula that calculates the forecasted sales based on the parameter's value.

1. Right-click in the empty space of the Data pane again and select "Create Calculated Field..."
2. Name this calculation Projected Sales.
3. In the formula box, type the following expression:

[Sales] * (1 + [Sales Growth Forecast %])

This formula is straightforward:

• [Sales] refers to your original sales measure.
• [Sales Growth Forecast %] refers to the parameter you just created. Tableau will use whatever value is currently selected on the slider.
• (1 + [Sales Growth Forecast %]) effectively calculates the growth multiplier (e.g., if the user selects 15%, this becomes 1.15).

1. Click OK. You'll now have a new measure called Projected Sales available to use in your charts.

Step 3: Build Your Visualization

Now we can use both our original sales figures and our new projected sales to build an insightful visualization.

1. Let’s start by building a simple bar chart. Drag your Order Date (or any time-based dimension) to the Columns shelf and set it to MONTH.
2. Drag the original Sales measure to the Rows shelf. You now have a basic chart showing your actual sales over time.
3. Next, drag your new Projected Sales measure to the Rows shelf, right beside the Sales measure. Tableau might create two separate charts.
4. To combine them, right-click the Projected Sales pill on the Rows shelf and select "Dual Axis." This will overlay the two charts.
5. On the Marks card, you now have settings for both Sales and Projected Sales. For clarity, change the mark type for Sales to Bar and the mark type for Projected Sales to Line or Circle. This visually differentiates the actual data from the forecast. You may also want to sync the axes by right-clicking the second y-axis and clicking Sync Axes to make sure the data scale matches up.

You're done! Now, you can move the Sales Growth Forecast % slider. As you do, you'll see the "Projected Sales" line move up and down in real-time, giving you and your team an instant understanding of different growth scenarios.

Advanced Ideas for 'What-If' Dashboards

Once you've mastered the basics, you can apply this concept to more complex and powerful scenarios.

Cost and Profitability Analysis

Create a parameter for "COGS % Increase." Then, build a calculated field for Profitability:

[Projected Profit] = SUM([Sales]) - (SUM([Cost of Goods Sold]) * (1 + [COGS % Increase]))

This allows you to model how supply chain cost increases might eat into your bottom line.

Using Multiple Parameters

You can use more than one parameter in a single dashboard. For example, a marketing manager might want to model changing two variables at once:

• Parameter 1: Ad Spend Increase ($)
• Parameter 2: Conversion Rate Uplift %
• Calculated Field: Projected Leads = ([Existing Traffic] + ([Ad Spend Increase ($)] / [Cost Per Click])) * ([Existing Conversion Rate] * (1 + [Conversion Rate Uplift %]))

This lets teams explore complex trade-offs and see how different combinations of inputs could affect their key metrics.

Categorical "What-If" Analysis

Parameters aren’t just for numbers. You can create a parameter with a list of strings to let users choose between different scenarios. For instance, a parameter named "Market Scenario" could have a list of allowable values like "Aggressive Growth," "Moderate Growth," and "Conservative."

You would then use a CASE statement in your calculated field to apply different logic based on the user's selection:

CASE [Market Scenario]
WHEN "Aggressive Growth" THEN SUM([Sales]) * 1.50
WHEN "Moderate Growth" THEN SUM([Sales]) * 1.25
WHEN "Conservative" THEN SUM([Sales]) * 1.10
END

This approach gives users pre-defined scenarios to choose from, which can be useful for standardized financial planning and reporting.

Final Thoughts

Learning how to model what-if scenarios in Tableau is a game-changer. It elevates your dashboards from backwards-looking reports into dynamic, forward-looking tools that fuel strategic discussions. By combining parameters with calculated fields, you can give anyone in your organization the power to explore possibilities, understand sensitivities, and ultimately make more confident, data-driven decisions about the future.

Mastering tools like Tableau takes time, and the learning curve for advanced analysis can be steep. That’s why we built Graphed. We wanted to make powerful data analysis accessible without the hours of frustration. Instead of wrestling with calculated fields and parameters, you can just ask questions in plain English – like "create a dashboard projecting our sales with a 15% increase next quarter" – and get a live, interactive dashboard built for you in seconds. It allows you to connect all your data sources so you can turn hours of manual report building into a simple conversation and get back to finding insights instead of just finding the right formula.