1Raw data:
2Q1: 150, Q2: 180, Q3: 210, Q4: 195
3 
4Observation từ số: "Q3 cao nhất"
5 
6Observation từ chart: 
7- Q3 cao nhất
8- Uptrend Q1→Q3
9- Q4 giảm nhẹ (potential concern)
10- Growth rate giảm dần

1Dataset 1: Linear relationship
2Dataset 2: Quadratic relationship  
3Dataset 3: Perfect line + 1 outlier
4Dataset 4: Vertical line + 1 outlier
5 
6Statistics: Identical
7Visualization: Completely different stories!

1Table với 1000 rows
2→ Brain: "Overload, cannot process"
3 
4Chart summary
5→ Brain: "Got it in 3 seconds"

1Bạn muốn show gì?
2    │
3    ├── Comparison → Bar/Column Chart
4    │
5    ├── Trend over time → Line Chart
6    │
7    ├── Part-to-whole → Pie/Donut (≤5 parts)
8    │
9    ├── Distribution → Histogram/Box Plot
10    │
11    ├── Relationship → Scatter Plot
12    │
13    └── Composition → Stacked Bar/Area

1Bad: Pie với 15 slices → Không đọc được
2Good: Bar chart horizontal → So sánh dễ

1Bad: 3D Pie → Distort proportions
2Good: 2D variants → Accurate reading

1Bad: 2 Y-axes với scales khác nhau → Misleading
2Good: Separate charts hoặc normalize data

1Bad: Y-axis bắt đầu từ 95 → Small change trông lớn
2Good: Y-axis từ 0 hoặc clearly labeled

1✅ Limit to 5-7 colors max
2✅ Use colorblind-friendly palettes
3✅ Consistent colors across dashboard
4✅ Gray for context, color for focus

1❌ Rainbow colors (hard to distinguish)
2❌ Red = Good, Green = Bad (reverse psychology)
3❌ Same color, different meanings
4❌ Bright colors for background

1Colorblind-safe palette:
2#1f77b4 (Blue)
3#ff7f0e (Orange)  
4#2ca02c (Green)
5#d62728 (Red)
6#9467bd (Purple)
7#8c564b (Brown)
8 
9Sequential (single hue):
10#deebf7 → #9ecae1 → #3182bd → #08519c
11 
12Diverging:
13#d7191c → #fdae61 → #ffffbf → #a6d96a → #1a9641
14(Red)                (Yellow)              (Green)

1Bad (low data-ink ratio):
2┌──────────────────────────────────────┐
3│ ████ Heavy gridlines                 │
4│ ████ 3D effects                      │
5│ ████ Decorative elements             │
6│ ████ Redundant labels                │
7└──────────────────────────────────────┘
8 
9Good (high data-ink ratio):
10┌──────────────────────────────────────┐
11│                                      │
12│   ▬▬▬  Clean, minimal design         │
13│   ▬▬▬▬▬  Focus on data               │
14│   ▬▬▬▬▬▬▬                            │
15└──────────────────────────────────────┘

1[Chart A] [Chart B]     ← Related metrics
2 
3[Chart C]               ← Different category

1● Sales Q1  ● Sales Q2  ● Sales Q3  ← Blue dots
2■ Costs Q1  ■ Costs Q2  ■ Costs Q3  ← Red squares

1┌─────────────────┐
2│ Revenue Section │
3│ [Chart] [KPI]   │
4└─────────────────┘

1Most Important
2    ↓
3████████████  Large, bold, top position
4    ↓
5████████  Medium, prominent
6    ↓
7████  Smaller, supporting
8    ↓
9Least Important

11. SETUP (Context)
2   "Q3 revenue was $2.5M..."
3 
42. CONFLICT (Problem/Opportunity)
5   "...but growth slowed to 5% vs 15% Q2"
6 
73. RESOLUTION (Insight/Action)
8   "Analysis shows: Marketing spend dropped 20%
9    Recommendation: Increase budget by $50K"

1Chart với annotations:
2 
3    Revenue Trend
4    │
5150 ┤                    ★ Campaign launched
6    │                   ╱
7100 ┤        ←─ Seasonal dip
8    │       ╱
9 50 ┤──────╱
10    └────────────────────────
11     J  F  M  A  M  J  J  A

1┌─────────────────────────────────────────────────────┐
2│                    TITLE                            │
3│              Key insight in subtitle                │
4├────────────────┬───────────────┬───────────────────┤
5│                │               │                   │
6│   KPI 1        │    KPI 2      │     KPI 3         │  ← At-a-glance
7│   $2.5M ▲12%  │    150K ▼3%  │     95% ▬         │
8│                │               │                   │
9├────────────────┴───────────────┴───────────────────┤
10│                                                     │
11│              MAIN VISUALIZATION                     │  ← Core story
12│                                                     │
13│                                                     │
14├────────────────────────┬────────────────────────────┤
15│                        │                            │
16│   Supporting Chart 1   │   Supporting Chart 2       │  ← Details
17│                        │                            │
18└────────────────────────┴────────────────────────────┘
19│             Filters: Date | Region | Product       │  ← Interactivity
20└─────────────────────────────────────────────────────┘

1Make important data POP:
2 
3Before: ■ ■ ■ ■ ■ ■ ■ ■ (all same)
4 
5After:  ■ ■ ■ ■ █ ■ ■ ■ (target highlighted)
6               ↑
7           "This one!"

1Bad:                    Good:
2   100│     ▲           100│
3    98│    ╱             50│     slight
4    96│___╱               0│___▬▬▬▬ increase
5     Looks like 50%        Actually 4%
6     increase

1Show only good months
2→ "Sales are up!"
3 
4Show full year
5→ "Actually, we're down 10% YoY"

1Pie chart for:
2- More than 5 categories
3- Values that don't sum to 100%
4- Showing trends

110 charts on 1 screen
2→ Information overload
3→ No clear message

1┌────────────────────────────────────────┐
2│  3D Pie Chart with 12 slices           │
3│  Rainbow colors                        │
4│  Legend far from chart                 │
5│  No title                              │
6│  Y-axis starts at 1000                 │
7│  Dual axis with different scales       │
8└────────────────────────────────────────┘
9 
10List 6 problems and suggest fixes.