Building Dashboards (Power BI / Tableau)

Power BI vs Tableau

| Feature | Power BI | Tableau | |---------|----------|---------| | Cost | $10-20/user | $15-70/user | | Ease of use | ★★★★★ | ★★★★☆ | | Microsoft integration | Excellent | Limited | | Customization | Good | Excellent | | Market share | #1 in business | #1 in enterprise |

Recommendation: Learn Power BI first (easier, cheaper, more jobs).

Power BI Basics

1. Data Import

Connect to: Excel, SQL, CSV, APIs, web

// Example data source
= Excel.Workbook(File.Contents("C:\\data\\sales.xlsx"))

2. Data Model

Create relationships between tables (like SQL joins).

Example:

• Sales table → Product table (via product_id)
• Sales table → Customer table (via customer_id)

3. DAX Formulas (Data Analysis Expressions)

Calculate total revenue:

Total Revenue = SUM(Sales[Amount])

Calculate YoY growth:

YoY Growth =
DIVIDE(
    [Total Revenue] - CALCULATE([Total Revenue], SAMEPERIODLASTYEAR(Calendar[Date])),
    CALCULATE([Total Revenue], SAMEPERIODLASTYEAR(Calendar[Date]))
)

Top 10 customers:

Top 10 Customers =
TOPN(10, ALL(Customers[Name]), [Total Revenue], DESC)

4. Visualizations

Drag & drop fields to create:

• Card (single number)
• Bar/Column chart
• Line chart
• Table/Matrix
• Map
• Slicers (filters)

5. Interactive Filters

Add slicers for:

• Date range
• Region
• Product category
• Customer segment

Tableau Basics

1. Connect to Data

Similar to Power BI - Excel, SQL, CSV, etc.

2. Sheets & Dashboards

• Sheet = Single visualization
• Dashboard = Multiple sheets combined

3. Calculated Fields

Total Revenue:

SUM([Amount])

Profit Margin:

([Revenue] - [Cost]) / [Revenue]

Running Total:

RUNNING_SUM(SUM([Amount]))

4. Parameters

Create interactive inputs:

• Date picker
• Metric selector (Revenue vs Profit)
• Top N filter

Dashboard Design Workflow

Step 1: Define Purpose

Questions to answer:

• Who is the audience? (Executive, analyst, operations)
• What decisions will this drive?
• How often will it be viewed?

Step 2: Choose Metrics

Executive Dashboard:

• Revenue, Profit, Growth %
• Top products, regions
• Trends

Sales Dashboard:

• Sales by rep
• Pipeline status
• Conversion rates

Step 3: Sketch Layout

F-Pattern example:

Step 4: Build in Tool

Import data → Create measures → Build visuals → Arrange layout

Step 5: Add Interactivity

• Slicers/filters
• Drill-through
• Tooltips
• Buttons

Real Example: Sales Dashboard

Goal: Track sales performance by region and product.

Power BI Steps:

1. Import data

   • Sales table
   • Products table
   • Regions table

2. Create relationships

   • Sales → Products (product_id)
   • Sales → Regions (region_id)

3. Build measures

   measure.daxDAX

   Copy code

   Total Sales = SUM(Sales[Amount])
   Target Achievement = DIVIDE([Total Sales], [Target])

4. Create visuals

   • Card: Total Sales
   • Bar: Sales by Region
   • Line: Monthly Trend
   • Table: Top Products

5. Add slicers

   • Date range
   • Region
   • Product category

Best Practices

✅ One page, no scrolling — All key info visible ✅ Limit to 5-7 visuals — Don't overcrowd ✅ Consistent colors — Same metric = same color ✅ Mobile-friendly — 40% of views are mobile ✅ Fast load time — Optimize data model ✅ Clear titles — Every visual labeled

Performance Tips

1. Limit data — Filter to recent dates
2. Use aggregations — Don't load raw rows
3. Optimize DAX — Avoid nested CALCULATEs
4. DirectQuery vs Import — Import is faster

Summary

✅ Power BI easier for beginners, Tableau more customizable ✅ DAX/Calculated Fields for custom metrics ✅ F-pattern layout for dashboards ✅ Interactive filters enhance usability ✅ Optimize for performance

Next: Statistics for Data Analytics! 📈