36.14 Marketing and Digital Ads
Performance-marketing interviews ask cost per order and return on ad spend (ROAS), and they ask whether the order row actually has a campaign id (Module 35.7). Impressions and clicks are easy to celebrate and easy to waste. CTR (clicks divided by impressions) is a diagnostic, not the decision.
| KPI | What the number means | Who uses it | Action it drives |
|---|---|---|---|
| CPA (cost per order) | Spend divided by attributed orders. | Media buyer | A high CPA stops or rewrites that campaign. |
| ROAS | Attributed sales divided by spend. | Marketing lead | Under 1 means the campaign returned less sales than it cost. Pause it in the practice file. |
| CTR | Clicks divided by impressions. | Only as a diagnostic | A high CTR with no orders is a curious audience, not a result. |
Fictional sample rows. One month. Every order below is attributed. Campaign names are labels, not real ads.
| Campaign | City | Impressions | Clicks | Spend | Orders | Sales |
|---|---|---|---|---|---|---|
| Diwali Pune | Pune | 1,00,000 | 2,000 | ₹20,000 | 100 | ₹80,000 |
| Monsoon Nashik | Nashik | 20,000 | 800 | ₹8,000 | 80 | ₹40,000 |
| Ganesh Kolhapur | Kolhapur | 80,000 | 400 | ₹10,000 | 20 | ₹15,000 |
| Weekend Nagpur | Nagpur | 10,000 | 500 | ₹5,000 | 50 | ₹30,000 |
| Clearance Mumbai | Mumbai | 5,000 | 250 | ₹2,500 | 40 | ₹12,000 |
| New user Sambhaji | Sambhaji Nagar | 60,000 | 300 | ₹9,000 | 15 | ₹6,000 |
Worked from those rows.
- Impressions 2,75,000. Clicks 4,250. Spend ₹54,500. Orders 305. Sales ₹1,83,000.
- CTR is 4,250 ÷ 2,75,000 = 1.5%.
- CPA is 54,500 ÷ 305 = ₹179 (nearest rupee).
- ROAS is 1,83,000 ÷ 54,500 = 3.36.
Diwali Pune: CPA 20,000 ÷ 100 = ₹200, ROAS 80,000 ÷ 20,000 = 4.00. Monsoon Nashik: CPA 8,000 ÷ 80 = ₹100, ROAS 40,000 ÷ 8,000 = 5.00. Ganesh Kolhapur: CPA 10,000 ÷ 20 = ₹500, ROAS 15,000 ÷ 10,000 = 1.50, on 80,000 impressions. Sambhaji Nagar ROAS is 6,000 ÷ 9,000 = 0.67.
| Good KPI | Vanity metric | |
|---|---|---|
| From the same rows | Monsoon Nashik CPA ₹100 and ROAS 5.00 | Diwali and Ganesh impressions (1,00,000 and 80,000) |
| Why | Nashik spent less and returned five rupees of sales per rupee. | Ganesh looks like a big campaign. It brought 20 orders at ₹500 each. Sambhaji returned 67 paise per rupee. |
What the manager does. The Nashik buyer keeps Monsoon and may test a small extra spend in the practice file, still labelled fictional. The Pune buyer keeps Diwali (ROAS 4) but does not judge it by the 1,00,000 impressions. The Kolhapur buyer pauses Ganesh. Clearance Mumbai is the quiet winner: CPA 2,500 ÷ 40 = ₹62, ROAS 12,000 ÷ 2,500 = 4.80, on only 5,000 impressions. Small is allowed to win.
Ravindra Bagale's Tip
Many students calculate ROAS where the order has a blank campaign. Call the blank Others, and do not join it to spend and call it ROAS. Use attributed orders only. Try it once more, then move on.
Ravindra Bagale's Tip – मराठी
बरेच students order वर campaign blank असतानाही ROAS काढतात. Blank ला Others म्हणा, आणि त्याला spend शी जोडून ROAS म्हणू नका. फक्त attributed orders वापरा. पुन्हा एकदा करून बघा, मग पुढे जा.
Ravindra Bagale's Tip – हिंदी
बहुत से students order पर campaign blank होने पर भी ROAS निकालते हैं. Blank को Others कहो, और उसे spend से जोड़कर ROAS मत कहो. सिर्फ़ attributed orders इस्तेमाल करो. एक बार फिर करके देखो, फिर आगे बढ़ो.