Western Governors University

D599: Data Preparation and Exploration

A guide to WGU's D599, where MS Data Analytics students clean, wrangle and explore data and interpret descriptive and inferential statistics.

Updated October 2026 · 5 min read

D599 Data Preparation and Exploration is a three-unit course in the second term of WGU's Master of Science in Data Analytics. WGU describes it as applying analytical programming skills to the early steps of the data analytics life cycle.

The course covers cleaning data for structure, accuracy and quality; interpreting descriptive and inferential statistics and visualizations; and wrangling data for later analysis. It introduces hypothesis testing with a focus on parametric tests and the skills to explain findings within an organization.

The listed prerequisites are The Data Analytics Journey, Data Management and Analytics Programming.

Course at a Glance

ItemDetails
UniversityWestern Governors University
Course codeD599
LevelGraduate (MS Data Analytics)
PrerequisitesThe Data Analytics Journey, Data Management, Analytics Programming
Standard pathTerm 2, 3 competency units
Typical workData dictionary interpretation, cleaning and wrangling, statistical interpretation

What D599 Covers

Competency (WGU wording, summarized)What it means in practice
Interprets a data dictionary to understand the data setReading variable definitions, types and units
Interprets probability, descriptive and inferential statistics, and visualizationSummaries, distributions, confidence and tests
Wrangles data to ensure accuracy, format and integrityFixing missing values, duplicates, types and outliers

Key Concepts Explained

Cleaning Decisions

Every cleaning step is a decision with consequences. Dropping rows with missing values can bias results; imputing values changes distributions. Document what you did and why.

Illustration (hypothetical): A column of customer ages contains 999 as a placeholder for unknown. Treating 999 as a real age distorts the mean. The cleaner approach is to recode it as missing, check how many are affected and note the handling.

Descriptive Versus Inferential Statistics

Descriptive statistics summarize the data you have. Inferential statistics use a sample to say something about a larger population, with uncertainty.

Hypothesis Testing

State the null and alternative hypotheses, choose a suitable parametric test, check assumptions, compute the result and interpret the p-value in context. Say what the result means for the business question, not only whether it is significant.

Typical Assignments and How to Approach Them

Task typeWhat it testsHow to approach it
Data dictionary and profilingUnderstanding dataSummarize each variable and flag quality problems
Cleaning and wranglingTechnical judgmentRecord every change and its rationale
Statistical interpretationApplied statisticsMatch test to data, check assumptions, explain results

A Repeatable Cleaning Workflow

A consistent order of operations avoids mistakes.

  1. Read the data dictionary and note each variable's meaning and type.
  2. Profile the data: counts, missing values, ranges and duplicates.
  3. Fix types and formats so values are comparable.
  4. Handle missing values and outliers with a stated reason.
  5. Explore with summaries and charts.
  6. Test hypotheses where required and interpret the results.

Reading Statistics and Visuals

The second competency covers probability, descriptive and inferential statistics, and visualization. When you present a chart, say what it shows, what pattern matters and what limits apply. A histogram reveals shape and outliers; a box plot compares groups; a scatter plot shows relationships. Pair each with a sentence of interpretation.

A Short Cleaning Walkthrough

Imagine a customer file with a date column stored as text in two formats, a few duplicate rows and some blank income values. Steps: convert both date formats to one, drop exact duplicates and record how many, then decide on the blank incomes.

If only a small share are missing, you might remove them; if many are missing, you might fill with the median and note the effect. Compare summary statistics before and after to show what changed.

Connecting to Earlier Courses

D599 builds on the three courses before it. From The Data Analytics Journey, bring the habit of starting with the question. From Data Management, bring comfort with data types and structure.

From Analytics Programming, bring the ability to script a repeatable process. Reviewing short notes from each before you begin will make the cleaning and testing tasks feel like a continuation rather than a new start.

Where Students Get Stuck

Study Tips for D599

How We Help with D599

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Frequently Asked Questions

What does D599 cover?

Data cleaning, descriptive and inferential statistics, visualization, wrangling and introductory hypothesis testing.

What are the prerequisites?

The Data Analytics Journey, Data Management and Analytics Programming.

Where is it in the degree?

Term two of the MS Data Analytics standard path.

Which tests are covered?

The description focuses on parametric tests.

Is programming needed?

Yes, it applies analytical programming skills.

Can GradeEssays complete my assessment?

No. We provide tutoring, custom answers, editing and feedback only.