6.1 Why Visualize Data?

Numerical summaries are essential, but they do not always tell the full story. Two datasets can have similar means and standard deviations while differing greatly in shape, clustering, outliers, or the relationship among variables. A visualization can reveal those differences immediately.

Visualizations can help you:

See the shape of a distribution, such as whether it is symmetric or skewed
Identify outliers or unusual values
Understand variability and spread
Compare groups
Detect relationships, changes, or trends
Notice possible data-entry or measurement problems

Visualizations in Practice

Visualizations are useful both while analyzing data and while communicating results.

During analysis, a graph can help you inspect the data before running an inferential test. For example, a histogram can reveal skew, a box plot can reveal possible outliers, and a scatterplot can reveal a nonlinear relationship that a correlation coefficient alone might hide.

When communicating results, a well-designed graph can summarize a large amount of information efficiently. This is especially useful because journal articles, professional reports, presentations, and public-facing materials often need to communicate findings to readers who may not have strong statistical backgrounds.

Exploration and Communication

The graph you use to explore your data does not always need to be the graph you use to present your findings.

Exploratory visualizations help you understand the data, check assumptions, and notice unusual patterns. They may include more detail than you would show in a final report.
Communication visualizations emphasize the pattern most relevant to the research question and should be understandable without requiring the reader to inspect the dataset.

jamovi provides visualizations in several places. Exploration → Descriptives remains especially useful for quickly inspecting distributions and possible outliers. The Plots tab provides more control over the appearance and labeling of graphs intended for communication.

Key Takeaway

Descriptive statistics and visualizations work together:

Statistics provide precise numerical summaries.
Visualizations provide an overall picture of the data.

Using both allows you to better understand and communicate your results.

Remember

Always visualize your data. You never know what a numerical summary may be hiding.

Here’s a video walking through why it is so important to look at your data.