Unveiling the Power of Spline Charts in Data Visualization

Enos Otieno Juma
Bold BI
Published in
6 min readJan 5, 2024
The Power of Spline Charts in Data Visualization

Spline charts stand tall in data visualization as invaluable visuals for presenting continuous data trends with remarkable clarity and precision. From their ability to smooth out erratic fluctuations to seamlessly connecting data points, these charts offer a visual narrative that simplifies complex information. In this blog, we delve into the intricacies of spline charts, exploring their functionalities, applications across various industries, and the art of harnessing their potential to reveal insightful trends hidden within datasets.

So, what is a spline chart, and why are they important?

A spline chart is a graphical tool designed to present data through a seamless curve connecting plotted points. This continuous curve makes visualizing trends and patterns over a range easier, offering a more intuitive understanding of data behavior between recorded observations.

Spline Chart Example in Bold BI
Spline Chart Example in Bold BI

The importance of visualizing data insights through spline charts

Spline charts are essential in visualizing data insights due to the following reasons:

  • Emphasizing smooth trends: Spline charts showcase trends or patterns in data by highlighting the smooth flow between points. This emphasis on continuity aids in visualizing data trends more distinctly.
  • Enhancing visual appeal: The curved lines in spline charts contribute to their aesthetic appeal, making data representation more engaging and easily understandable.
  • Clarifying complex data: Spline charts are beneficial for illustrating complex datasets in a more digestible manner. The smooth curves can simplify intricate information, enabling more precise insights and interpretations.
  • Improving data interpretation: Spline charts facilitate straightforward interpretation by presenting data more smoothly, enabling users to grasp trends or anomalies better.
  • Enhancing insight communication: Utilizing spline charts improves communicating insights derived from data, making presentations or reports more compelling and informative.

When is a spline chart effective?

Here are some circumstances in which you might prefer to use a spline chart:

  • To show trends over time or continuous data.
  • To show minimums and maximums in data series through the curvature of a spline.
  • To display smoother transitions between data points.
  • To visualize data that requires interpolation between points.
  • When the dataset contains seasonal or cyclical patterns.
  • To compare multiple data sets with subtle variations.
  • When you need to emphasize the rate of change between points.

However, there are also times when a spline chart might not be the best choice. Let’s look at them in detail.

When not to use a spline chart

Do not use spline charts for the following:

  • When data is categorical or nominal.
  • When precise data points are essential and interpolation could cause confusion.
  • When the data contains outliers that could distort the spline curve.
  • When the relationship between variables is known to be linear.
  • When the data is discontinuous or has abrupt changes.
  • When data points are categorical rather than numerical or time-based.

How to configure the spline chart in your application

To configure a spline chart, drag and drop it from the toolbox onto a canvas, resize it, and then click the Properties icon in the configuration panel. Assign data from an existing source by dragging and dropping the data from Measures and Dimensions into the required field to the Columns section. To learn more about configuring spline charts in Bold BI, check out this documentation.

Best practices for spline charts

To create an effective spline chart, consider the following best practices:

  • Select appropriate data: Spline charts are ideal for continuous, logically ordered data such as time series.
  • Reduce data points: Simplify your chart by aggregating data to maintain trends and improve readability.
  • Be wary of over-smoothing: Ensure the spline’s smoothness accurately represents the data without creating false trends.
  • Simplify the chart: Avoid clutter by limiting the number of series or using alternative visualizations for complex data.
  • Maintain consistent scaling: Use scales on axes that accurately represent the data without distortion.
  • Use tooltips and labels effectively: Employ tooltips for added information and data labels for clarity without overcrowding the chart.
  • Choose clear colors and styles: Utilize contrasting colors for visibility and distinct, harmonious colors for comparing series.
  • Review and test the chart: Ensure the chart’s message is clear and not misleading; validate its effectiveness with your audience.

Applications of spline charts in various industries

Spline charts find versatile applications across multiple industries because they can handle complex data. Here are examples of their real-world use:

1. Finance: Inventory

The inventory metric in finance measures the speed at which a company replenishes goods within a period after they are sold. It is crucial for assessing the efficiency of inventory management and optimizing cash flow. Utilizing a spline chart to visualize inventory data can highlight trends and seasonal fluctuations in inventory management, allowing for better prediction and strategic planning.

Inventory
Inventory

2. Marketing: page visits vs. product sales

In marketing, tracking page visits against product sales is essential for understanding the effectiveness of online marketing efforts and the conversion rate of visitors to customers. A spline chart is particularly useful for such data, as it seamlessly connects data points, making it easier to see the relationship between marketing activities and sales outcomes to identify any discrepancies that might require action.

Page Visit vs. Product Sales
Page Visit vs. Product Sales

3. Agile: Completed story points over time

This metric is used in Agile project management to track the amount of work a team completes in a given iteration, providing insight into team velocity and project progress. A spline chart is crucial for visualizing this metric as it shows the flow and variations of team performance across iterations, helping to predict future sprint capacities and adjust workloads accordingly.

Completed Story Points Over Time
Completed Story Points Over Time

4. Information technology: Planned vs. completed work items

This metric tracks the number of tasks or work items scheduled to be completed in a specific timeframe against the actual number completed. This is key in the IT industry to assess a team’s efficiency and the accuracy of their planning process. IT managers can easily visualize the gap between planned and actual results using a spline chart, helping identify areas for process improvement and better project planning.

Planned vs. Completed Work Items
Planned vs. Completed Work Items

5. Sales: Sales forecast

A sales forecast projects sales revenue for a period. It is a critical metric for driving business strategy, resource allocation, and financial planning in the sales industry. A spline chart can effectively display the anticipated sales trajectory against actual sales, offering a clear visual representation that can aid in adjusting sales strategies and expectations in real time.

Planned vs. Completed Work Items
Sales Forecast

6. Government: Accident trends over time

In government, tracking accident trends over time is vital for identifying patterns, evaluating the effectiveness of safety measures, and allocating resources for public safety initiatives. Utilizing a spline chart to represent this data can provide a smooth and intuitive visualization of long-term trends and seasonal variations, which can be instrumental in policy-making and preventive action planning.

Accident Trends over Time
Accident Trends over Time

These spline charts analyze and communicate industrial data trends essential for informed decisions in a specific sector. Bold BI simplifies the creation and management of spline charts with its intuitive dashboard, enabling real-time monitoring and easy interpretation of intricate data patterns. For more Bold BI dashboard examples, visit this link.

In conclusion, spline charts are compelling tools for smoothing out the noise in data, providing clear insights and trends that can drive informed decisions. Embrace their power to transform complex datasets into visually intuitive narratives and unlock a deeper understanding of your data’s story.

Originally published at https://www.boldbi.com on January 5, 2024.

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Enos Otieno Juma
Bold BI
Writer for

Technical writer and content reviewer at Syncfusion.