| name | impression-share-diagnostics |
| description | Impression share analysis and root cause diagnosis for Google Ads Search campaigns. Auto-invoke when investigating underspending, analyzing auction competitiveness, or diagnosing budget vs. quality issues. Interprets Search IS, Budget Lost IS, and Rank Lost IS metrics in smart bidding context. |
| allowed-tools | ["Read"] |
Impression Share Diagnostics Skill
Purpose: Provides expert analysis of impression share metrics to diagnose root causes of underspending and auction performance issues in Google Ads Search campaigns.
Type: Domain knowledge skill (auto-invoked)
Core Impression Share Metrics
Search Impression Share (Search IS)
What it measures: Percentage of impressions you received out of total eligible impressions
How to interpret:
- >80%: Excellent - capturing most available impressions
- 50-80%: Good - moderate market coverage
- 30-50%: Limited - missing significant opportunity
- <30%: Very limited - major opportunity loss
Note: Higher is better, but 100% is rarely achievable or necessary
Budget Lost Impression Share (Budget Lost IS)
What it measures: Percentage of impressions lost due to budget constraints
How to interpret:
- <10%: Budget is sufficient for current demand
- 10-30%: Moderate budget constraint (minor opportunity loss)
- 30-50%: Significant budget constraint (primary limiting factor)
- >50%: Severe budget constraint (major spend potential untapped)
Primary indicator: If high, increasing budget will likely increase spend
Rank Lost Impression Share (Rank Lost IS)
What it measures: Percentage of impressions lost due to ad rank (quality + bid)
How to interpret:
- <10%: Excellent competitive position
- 10-30%: Good competitive position (normal)
- 30-60%: Moderate competitive disadvantage
- >60%: Significant competitive disadvantage
CRITICAL CONTEXT: Rank Lost IS is informational, not a primary optimization target
Smart Bidding Context (CRITICAL)
Most Portfolio Campaigns Use Smart Bidding
Common bidding strategies:
- Max Conversions (no target) - Automated, no manual bid control
- Max Conversion Value (no target) - Automated, ROAS focus
- Max Clicks (with optional max CPC limit) - Automated, traffic focus
YOU CANNOT MANUALLY ADJUST BIDS - Google's algorithm controls them.
Primary Control Lever: Monthly budget (translates to daily budget)
Budget Management Philosophy:
- #1 Priority: Hit monthly spend targets (pacing)
- #2 Priority: Maintain acceptable CPA/ROAS goals
- Budget increases are CONSERVATIVE: 5-10% monthly budget increases
Root Cause Diagnosis Decision Tree
Scenario 1: Budget Too Low (Most Common)
Pattern:
- Budget Lost IS: >10% (any level of budget constraint)
- Rank Lost IS: >50% (high competitive pressure)
- Search IS: <70% (missing impressions)
What's happening:
- Google's algorithm wants to bid higher to compete
- Budget cap prevents it from spending more
- Algorithm is forced to bid conservatively to stay within budget
- Result: Lower bids → Worse ad rank → Lost impressions
Diagnosis: Budget is too low for competitive auction environment
Recommendation: Increase monthly budget by 5-10%
Why this works:
- With smart bidding, budget is the primary lever
- Higher budget → algorithm can bid more aggressively
- More aggressive bids → better ad rank → more impressions → more spend
Scenario 2: Quality Score Issues (Secondary)
Pattern:
- Rank Lost IS: >60% (very high)
- Budget Lost IS: <10% (budget is sufficient)
- CPA significantly above goals
- Search IS: Low despite budget availability
What's happening:
- Low quality score = higher cost per click
- Google charges more for lower quality ads
- Algorithm can't compete efficiently
- Result: Fewer impressions even with budget available
Diagnosis: Ad relevance, landing page, or keyword quality issues
Recommendation:
- Improve ad relevance (match ad copy to keywords)
- Improve landing page experience (speed, mobile, relevance)
- Refine keyword quality (remove low-performing keywords)
- Secondary to budget fixes - quality improvements take time
Scenario 3: Low Demand (Normal, Not a Problem)
Pattern:
- Search IS: >80% (capturing most impressions)
- Budget Lost IS: <10% (budget is sufficient)
- Rank Lost IS: <10% (good competitive position)
- Still underspending vs. budget
What's happening:
- You're capturing most available impressions
- Low search volume for these keywords
- This is NORMAL - not every keyword has high volume
Diagnosis: Account is operating efficiently, just low organic demand
Recommendation:
- Option 1: Accept that this is normal (low search volume markets)
- Option 2: Consider reducing budget to match actual demand
- Option 3: Expand targeting (new keywords, looser match types, new geos)
DO NOT increase budget in this scenario - you're already capturing available demand
Scenario 3a: Brand Campaign Demand Ceiling (Budget Reallocation)
Pattern:
- Brand campaign Search IS: >90% (near-maxed)
- Budget Lost IS: <10%
- Brand campaign spending 40-60% of allocated budget
- Other campaigns (GEO, BDRM) have lower IS (more headroom)
What's happening:
- Brand search demand is capped - not enough searches for "[Property] apartments"
- At 90%+ IS, you're capturing nearly all available brand demand
- Budget allocated to Brand cannot be spent
- Meanwhile, GEO/BDRM campaigns have impression share headroom
Diagnosis: Budget misallocation - too much budget on demand-capped Brand, not enough on campaigns with headroom
Recommendation:
- Reallocate budget from Brand → GEO or BDRM campaigns
- Brand continues capturing all available demand (just with smaller budget)
- GEO/BDRM can compete more aggressively with additional budget
- Total account spend increases toward daily target
Example:
Before reallocation:
- Brand: $20/day budget, $10/day actual (50% util), 94% IS
- GEO: $45/day budget, $27/day actual (60% util), 18% IS
- BDRM: $45/day budget, $20/day actual (44% util), 44% IS
Action: Move $5-10/day from Brand to GEO/BDRM
After reallocation:
- Brand: $12/day budget (still captures 94% IS)
- GEO: $50/day budget (can now compete for more of the 82% lost IS)
- BDRM: $48/day budget (can compete for more of the 56% lost IS)
Key Insight: You can't force demand that doesn't exist - put budget where there's opportunity
Scenario 4: Recent Budget Increase (Ramp-Up Period)
Pattern:
- Budget was increased in last 3-7 days
- Currently underspending vs. new budget
- Impression share metrics not yet stabilized
What's happening:
- Smart bidding algorithms need time to adjust
- Algorithm gradually increases bids after budget increase
- Normal ramp-up period (3-7 days typical)
Diagnosis: Normal ramp-up period after budget increase
Recommendation:
- No action needed
- Monitor for 3-5 more days
- If still underspending after 7 days, re-investigate
DO NOT increase budget again during ramp-up period
Impression Share Context for Different Campaign Types
Search Campaigns (GEO, Bedroom, Brand)
- Full IS metrics available: Search IS, Budget Lost IS, Rank Lost IS
- Use decision tree above to diagnose root cause
- Primary focus: Budget Lost IS (indicates spend potential)
Performance Max Campaigns
- NO impression share metrics available (different auction dynamics)
- Cannot use IS for diagnosis
- Alternative diagnostics:
- Budget utilization % (MTD spend ÷ MTD budget)
- Asset performance scores
- Auction insights (when available)
Demand Gen Campaigns
- Limited IS metrics (display network, different from search)
- Focus on: Reach, frequency, view rate
- Not applicable: Search IS decision tree
Display/Video Campaigns (Remarketing)
Key Diagnostic: Check for "Bid setting limited" status in Google Ads UI
Common Issue: Max CPC bid cap too restrictive on Maximize Clicks strategy
Pattern:
- Campaign status shows "Bid setting limited"
- Very low click volume despite budget availability
- Spending well below daily budget
Root Cause: Max CPC cap (e.g., $2-3) is lower than auction clearing prices for Display network. Campaign can't compete for impressions.
Standard Fix for Display Remarketing:
- Increase max CPC bid limit to $4.00 (standard floor)
- This provides headroom to compete while maintaining reasonable ceiling
Context: Accounts may use standardized content suitability settings which restrict available inventory. This means bid caps need to be higher ($4+) to compete in the smaller placement pool. If content suitability settings change, bid cap requirements may need adjustment.
Verification:
- Check campaign settings → Bidding → "Maximum CPC bid limit"
- If under $4.00, increase to $4.00
- Monitor for 2-3 days - spend should increase toward budget
Expected CPC Range: $2-3 after auctions normalize (the $4 cap acts as ceiling)
Note: Display campaigns don't have Search IS metrics - diagnose via campaign status and bid strategy settings
How to Interpret Rank Lost IS in Context
Common Misconception:
"Rank Lost IS is high (60-80%), so we need to improve quality score or increase bids"
Reality:
- Rank Lost IS is informational, not a target
- High Rank Lost IS (60-80%) is common in competitive auctions
- Don't optimize TO a specific Rank Lost IS target
- Use it to understand WHY underspending (competitive pressure signals budget need)
Correct Interpretation:
- High Rank Lost IS + High Budget Lost IS → Budget is the constraint
- High Rank Lost IS + Low Budget Lost IS → Quality/efficiency is the constraint
- Low Rank Lost IS + Low Budget Lost IS → No constraint (low demand)
Primary focus: Pacing variance and CPA/ROAS performance, not Rank Lost IS itself
Budget vs. Quality Trade-offs
When Budget Increase is Appropriate:
✅ Underspending vs. monthly budget (pacing variance >±8%)
✅ Budget Lost IS >10% (spend potential exists)
✅ CPA is acceptable or below goal
✅ ROAS is acceptable or above goal
✅ No recent budget increase in last 7 days
When Budget Increase is NOT Appropriate:
❌ CPA is significantly above goal (>20% over target)
❌ ROAS is below minimum threshold
❌ Recent budget increase within last 3-7 days (ramp-up period)
❌ Search IS >80% + Budget Lost IS <10% (low demand, not budget constraint)
❌ Quality score issues evident (very high CPA despite budget availability)
The Conservative Approach:
- Start with 5% budget increase (not 10-20%)
- Monitor for 5-7 days before additional increases
- Never increase budget >10% in single change (algorithm shock risk)
- Quality improvements are secondary to budget optimization
Integration with Underspending Investigation
How This Skill Fits:
This skill provides the Step 3: Impression Share Analysis framework for underspending investigations.
Typical Investigation Flow:
- Step 1: Check recent optimizations (ramp-up period check)
- Step 2: Analyze campaign spend patterns (which campaigns, budget structure)
- Step 3: USE THIS SKILL → Diagnose root cause via impression share
- Output: Budget recommendation or quality improvement recommendation
Expected Output from This Skill:
After analyzing IS metrics, you should be able to answer:
- What is the primary constraint? (Budget | Quality | Low Demand | Ramp-Up)
- What evidence supports this? (specific IS metric values)
- What action is recommended? (budget increase | quality improvement | monitor | reduce budget)
- Why will this work? (mechanism explanation)
Quick Reference: IS Patterns Cheat Sheet
| Search IS | Budget Lost IS | Rank Lost IS | Diagnosis | Recommendation |
|---|
| <70% | >30% | >50% | Budget too low | Increase budget 5-10% |
| <70% | <10% | >60% | Quality issues | Improve quality (secondary) |
| >80% | <10% | <10% | Low demand | Normal (or reduce budget) |
| Any | Any | Any | Recent budget ↑ | Monitor 3-5 more days |
| 50-70% | 10-30% | 30-60% | Mixed constraint | Increase budget 5% + monitor |
When to Use This Skill
Auto-Invoked When:
- Investigating underspending issues
- Analyzing impression share metrics
- Diagnosing auction competitiveness
- Determining budget vs. quality constraints
- User mentions "impression share", "lost IS", "rank lost", or "budget lost"
- Creating budget increase recommendations
- Explaining why campaigns are underspending
Data Sources Required:
- Google Ads API:
metrics.search_impression_share
- Google Ads API:
metrics.search_budget_lost_impression_share
- Google Ads API:
metrics.search_rank_lost_impression_share
- Campaign bidding strategy:
campaign.bidding_strategy_type
- Campaign CPA/ROAS:
metrics.cost_per_conversion, metrics.conversions_value_per_cost
CRITICAL: API Returns Decimals, Not Percentages
The Google Ads API returns impression share as decimals (0.0 to 1.0), NOT percentages.
| API Value | Actual Percentage |
|---|
| 0.2464 | 24.64% |
| 0.1017 | 10.17% |
| 0.0999 | 9.99% |
| 0.6337 | 63.37% |
When displaying to users or applying thresholds, always multiply by 100:
search_is_pct = row.metrics.search_impression_share * 100
print(f"Search IS: {search_is_pct:.1f}%")
print(f"Search IS: {row.metrics.search_impression_share:.2f}%")
Threshold comparisons must use percentage values (after multiplying by 100):
search_is = api_value * 100
if search_is > 80:
print("High impression share")
Using Impression Share as Demand Ceiling (Budget Viability Analysis)
The Pattern
When evaluating whether an ad group or campaign can absorb a budget increase (or sustain spend after pausing other segments), use impression share as a demand signal to calculate the spending ceiling.
Key Insight:
- Current spend tells you what you are spending
- Impression Share tells you what you could spend (the demand ceiling)
Formula
Potential Spend = Current Spend / (Search IS / 100)
Example
Scenario: Client asks to pause all ad groups except one single-geo ad group. Can it absorb the budget?
| Metric | Single Ad Group |
|---|
| Current spend | $91/month |
| Search IS | 15.8% |
| Potential ceiling | $91 / 0.158 = $577/month |
| Required budget | $1,800/month |
| Verdict | Will severely underpace (68% under) |
When to Use This
- Client asks to pause ad groups and consolidate budget into fewer segments
- Evaluating if a single geo/segment can absorb increased spend
- Predicting underspend risk before making changes
- Sizing addressable demand for a keyword set or geography
- Answering "can X absorb Y budget?"
Ad Group Level IS
Important: Search Impression Share is available at the ad group level, not just campaign level.
Query pattern:
SELECT
ad_group.name,
metrics.impressions,
metrics.cost_micros,
metrics.search_impression_share
FROM ad_group
WHERE campaign.name LIKE "%GEO%"
AND segments.date DURING LAST_30_DAYS
Nuances & Limitations
- This is a rough estimate, not exact
- Assumes similar CPCs at higher volume (CPCs may increase with more aggressive bidding)
- Smart Bidding may adjust behavior when segments change
- Works best for Search campaigns (PMAX has no IS metrics)
- The ceiling assumes 100% IS capture, which is rarely achievable in practice
Probability Assessment
Use the gap between potential ceiling and required budget to estimate underpacing risk:
| Gap | Probability of Underpacing |
|---|
| Ceiling < 50% of required | >90% (near certain) |
| Ceiling 50-75% of required | 70-90% (very likely) |
| Ceiling 75-100% of required | 40-70% (likely) |
| Ceiling > 100% of required | <40% (may work) |
Related Skills in This Repo
Built by Kurt Henninger. More free skills: github.com/fourteenwm/ppc-ai-skills
