Documentation standards in Power BI - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to add a description to a measure in Power BI.

Power BI

Measure = SUM(Sales[Amount])  -- [1]

Drag options to blanks, or click blank then click option'

A"Total sales amount"

B# Total sales amount

C/* Total sales amount */

D// Total sales amount

Attempts:

3 left

💡 Hint

Common Mistakes

Using // for comments which is not supported in DAX

Putting description as a string without comment syntax

In Power BI DAX, comments are added using /* comment */ syntax. This helps document the measure.

2fill in blank

medium

Complete the code to add a tooltip description to a Power BI visual.

Power BI

Visual.Tooltip = [1]

Drag options to blanks, or click blank then click option'

A"Shows total sales by region"

BSUM(Sales[Amount])

CCALCULATE(SUM(Sales[Amount]))

DSELECTEDVALUE(Region[Name])

Attempts:

3 left

💡 Hint

Common Mistakes

Using a measure or calculation instead of text

Not using quotes around the tooltip text

Tooltips are text descriptions that explain visuals. They should be strings describing the visual.

3fill in blank

hard

Fix the error in the DAX measure documentation comment.

Power BI

Total Sales = SUM(Sales[Amount]) [1]

Drag options to blanks, or click blank then click option'

A// Total sales amount

B/* Total sales amount */

C# Total sales amount

D-- Total sales amount

Attempts:

3 left

💡 Hint

Common Mistakes

Using // which is invalid in DAX

Using # or -- which are not comment syntax in DAX

DAX supports block comments with /* */. Using // or # causes errors.

4fill in blank

hard

Fill both blanks to create a descriptive title and subtitle for a Power BI report page.

Power BI

ReportPage.Title = [1]
ReportPage.Subtitle = [2]

Drag options to blanks, or click blank then click option'

A"Sales Overview"

B"2024 Q1 Results"

CSUM(Sales[Amount])

DCALCULATE(SUM(Sales[Amount]))

Attempts:

3 left

💡 Hint

Common Mistakes

Using measures or calculations instead of text

Not using quotes around text

Titles and subtitles should be descriptive text strings to help users understand the report content.

5fill in blank

hard

Fill all three blanks to document a calculated column with a description and format string.

Power BI

Profit Margin = DIVIDE(Sales[Profit], Sales[Amount]) [1]
FORMAT(Profit Margin, [2])  -- [3]

Drag options to blanks, or click blank then click option'

A/* Calculates profit margin ratio */

B"0.00%"

CProfit margin as percentage

D"#,##0.00%"

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect comment syntax

Using wrong format string without % sign

Not providing clear description

Use block comments for description, a proper format string for percentage, and a clear comment explaining the format.

Practice

1. Why is documentation important in Power BI reports?

easy

A. It hides data from users.

B. It increases the file size of the report.

C. It makes reports easier to understand and maintain.

D. It automatically fixes errors in data.

Solution

1. Step 1: Understand the purpose of documentation

   Documentation helps explain what the report does and how it works.

2. Step 2: Identify the benefit in Power BI context

   Clear documentation makes reports easier to use and maintain by others or yourself later.

3. Final Answer:

   It makes reports easier to understand and maintain. -> Option C

4. Quick Check:

   Documentation improves clarity = A [OK]

Hint: Documentation = easier understanding and maintenance [OK]

Common Mistakes:

• Thinking documentation changes report size
• Believing documentation hides data
• Assuming documentation fixes errors automatically

2. Which of the following is the correct way to add a comment in a DAX formula in Power BI?

easy

A. # This is a comment

B. // This is a comment

C.

D. /* This is a comment */

Solution

1. Step 1: Recall DAX comment syntax

   DAX uses double slashes (//) for single-line comments.

2. Step 2: Compare options with DAX syntax

   Only // This is a comment uses // which is correct for DAX comments.

3. Final Answer:

   // This is a comment -> Option B

4. Quick Check:

   DAX comments start with // = B [OK]

Hint: DAX single-line comments start with // [OK]

Common Mistakes:

• Using # which is for other languages
• Using HTML style comments
• Using /* */ which is not valid in DAX

3. Given this DAX measure with a comment:

SalesAmount = SUM(Sales[Amount]) // Total sales amount

What will be the output of this measure in a report?

medium

A. The sum of sales amounts plus the comment text

B. The text 'Total sales amount'

C. An error because of the comment

D. The sum of all sales amounts

Solution

1. Step 1: Understand how comments affect DAX measures

   Comments are ignored by the DAX engine and do not affect calculation.

2. Step 2: Evaluate the measure logic

   The measure sums the Sales[Amount] column values, so output is total sales amount.

3. Final Answer:

   The sum of all sales amounts -> Option D

4. Quick Check:

   Comments ignored, measure sums values = A [OK]

Hint: Comments do not affect measure output [OK]

Common Mistakes:

• Thinking comments become output text
• Assuming comments cause errors
• Believing comments add to calculation

4. You wrote this DAX measure:

Profit = SUM(Sales[Revenue]) - SUM(Sales[Cost]) // Calculate profit

But Power BI shows an error. What is the likely cause?

medium

A. The column names might be misspelled or missing.

B. DAX does not support comments at the end of a line.

C. You cannot subtract two SUM functions in DAX.

D. The comment syntax is incorrect in DAX.

Solution

1. Step 1: Check comment syntax validity

   The comment syntax // is valid in DAX, so comments are not the cause.

2. Step 2: Consider common errors in measure formulas

   Errors often come from misspelled or missing column names in SUM functions.

3. Final Answer:

   The column names might be misspelled or missing. -> Option A

4. Quick Check:

   Check column names first for errors = D [OK]

Hint: Check column names first when measure errors occur [OK]

Common Mistakes:

• Blaming comment syntax for errors
• Thinking SUM subtraction is invalid
• Assuming comments can't be inline

5. You want to document a complex Power BI report for your team. Which combination of documentation practices is best?

hard

A. Use clear names for tables and columns, add comments in DAX, and write descriptions for visuals.

B. Only add comments in DAX formulas; names and descriptions are optional.

C. Use vague names but add many comments in visuals only.

D. Skip comments and rely on team meetings to explain the report.

Solution

1. Step 1: Identify good documentation practices

   Clear names, comments, and descriptions help everyone understand the report easily.

2. Step 2: Evaluate options for completeness

   Use clear names for tables and columns, add comments in DAX, and write descriptions for visuals. combines all good practices: naming, commenting, and describing visuals.

3. Final Answer:

   Use clear names for tables and columns, add comments in DAX, and write descriptions for visuals. -> Option A

4. Quick Check:

   Combine naming, comments, descriptions = C [OK]

Hint: Combine clear names, comments, and descriptions for best docs [OK]

Common Mistakes:

• Relying only on comments or only on names
• Using vague names that confuse users
• Skipping documentation and relying on meetings