| name | anomaly-detector |
| description | Statistical anomaly detection in campaign metrics. Use when detecting spend spikes, CTR drops, budget runaway, metric outliers, or configuring automated alert thresholds. |
Anomaly Detector
Detect statistical anomalies in advertising campaign metrics using Z-score and IQR methods. Identifies spend spikes, sudden CTR/CVR drops, budget runaway events, and other metric outliers in real time. Provides automated alert threshold configuration and platform-specific query patterns for continuous monitoring.
Capabilities
- Z-Score Detection: Flag metrics that deviate >2ฯ from the rolling mean
- IQR (Interquartile Range) Detection: Robust outlier detection resistant to skewed distributions
- Spend Spike Alerts: Detect budget runaway before daily caps are exhausted
- CTR/CVR Drop Detection: Identify sudden performance degradation
- Multi-Platform Monitoring: Query patterns for Google Ads, Meta, LinkedIn, Reddit, TikTok, Microsoft Ads
- Threshold Configuration: Auto-calibrate alert sensitivity per metric and campaign maturity
- Composite Scoring: Combine multiple signals into a single anomaly confidence score
Workflows
1. Real-Time Spend Monitoring
1. Pull hourly spend data for active campaigns
2. Calculate rolling 7-day hourly average and standard deviation
3. Compare current hour spend against baseline
4. If Z-score > 2.5 โ WARNING alert
5. If Z-score > 3.5 โ CRITICAL alert (potential budget runaway)
6. Check if spend pacing exceeds 150% of expected daily run rate
7. Recommend: pause campaign or reduce bids if critical
2. Performance Drop Detection
1. Pull daily CTR and CVR for last 30 days
2. Compute IQR for each metric
3. Flag days where metric < Q1 - 1.5รIQR
4. Cross-reference with external events (platform outages, policy changes)
5. If drop persists >2 consecutive days โ investigate root cause
6. Check: ad disapprovals, audience exhaustion, competitor entry, landing page errors
3. Alert Threshold Calibration
1. Collect 30โ90 days of historical metric data
2. Compute per-metric baseline statistics (mean, std, percentiles)
3. Set WARNING threshold at 2ฯ deviation
4. Set CRITICAL threshold at 3ฯ deviation
5. For low-volume campaigns (<100 clicks/day): use IQR method (more robust)
6. For high-volume campaigns (>1000 clicks/day): use Z-score (more sensitive)
7. Review and adjust thresholds monthly as campaign matures
4. Cross-Platform Anomaly Correlation
1. Normalize metrics across platforms (Z-score per platform)
2. Detect simultaneous anomalies across multiple platforms
3. If correlated: likely external cause (market event, website outage)
4. If isolated: likely platform-specific issue (policy, auction change)
5. Generate incident report with affected campaigns and estimated impact
Reference Data
Detection Methods Comparison
| Method | Best For | Pros | Cons |
|---|
| Z-Score | High-volume, normally distributed data | Sensitive, quantifiable | Assumes normal distribution |
| Modified Z-Score (MAD) | Data with outliers in history | Robust to existing outliers | Less sensitive |
| IQR | Skewed distributions, low volume | No distribution assumption | Less granular thresholds |
| Rolling Window | Seasonal/trending data | Adapts to trends | Lag in detection |
| CUSUM | Detecting persistent shifts | Catches gradual drifts | Complex to tune |
| Isolation Forest | Multi-dimensional anomalies | Handles feature interactions | Requires training data |
Metric-Specific Thresholds (Defaults)
| Metric | WARNING (Z-score) | CRITICAL (Z-score) | Min Data Points |
|---|
| Hourly Spend | >2.0 | >3.0 | 168 (7 days) |
| Daily Spend | >2.5 | >3.5 | 30 days |
| CTR | < -2.0 | < -3.0 | 14 days |
| CVR | < -2.0 | < -3.0 | 14 days |
| CPC | >2.0 | >3.0 | 14 days |
| CPM | >2.5 | >3.5 | 14 days |
| Impression Share | < -2.5 | < -3.5 | 14 days |
| Quality Score | < -1.5 | < -2.5 | 7 days |
Platform Query Patterns
Google Ads (GAQL):
SELECT
campaign.name,
segments.date,
segments.hour,
metrics.cost_micros,
metrics.clicks,
metrics.impressions,
metrics.conversions,
metrics.ctr,
metrics.average_cpc
FROM campaign
WHERE segments.date DURING LAST_7_DAYS
AND campaign.status = 'ENABLED'
ORDER BY segments.date DESC, segments.hour DESC
Meta Ads (Marketing API):
GET /{ad_account_id}/insights
?level=campaign
&fields=spend,clicks,impressions,actions,ctr,cpc
&time_range={"since":"2026-02-27","until":"2026-03-06"}
&time_increment=1
&filtering=[{"field":"campaign.effective_status","operator":"IN","value":["ACTIVE"]}]
LinkedIn Ads:
GET /adAnalytics
?q=analytics
&dateRange.start.year=2026&dateRange.start.month=2&dateRange.start.day=27
&dateRange.end.year=2026&dateRange.end.month=3&dateRange.end.day=6
&timeGranularity=DAILY
&pivot=CAMPAIGN
&fields=costInLocalCurrency,clicks,impressions,externalWebsiteConversions
Anomaly Detection Algorithms (Python)
Z-Score Method
import numpy as np
from typing import List, Tuple
def detect_zscore_anomalies(
values: List[float],
window: int = 30,
warning_threshold: float = 2.0,
critical_threshold: float = 3.0,
) -> List[dict]:
"""Detect anomalies using rolling Z-score."""
arr = np.array(values, dtype=float)
anomalies = []
for i in range(window, len(arr)):
window_data = arr[i - window : i]
mean = np.mean(window_data)
std = np.std(window_data, ddof=1)
if std == 0:
continue
z_score = (arr[i] - mean) / std
if abs(z_score) >= critical_threshold:
anomalies.append({
"index": i,
"value": arr[i],
"z_score": round(z_score, 2),
"mean": round(mean, 2),
"std": round(std, 2),
"severity": "CRITICAL",
"direction": "spike" if z_score > 0 else "drop",
})
elif abs(z_score) >= warning_threshold:
anomalies.append({
"index": i,
"value": arr[i],
"z_score": round(z_score, 2),
"mean": round(mean, 2),
"std": round(std, 2),
"severity": "WARNING",
"direction": "spike" if z_score > 0 else "drop",
})
return anomalies
IQR Method
def detect_iqr_anomalies(
values: List[float],
multiplier: float = 1.5,
) -> List[dict]:
"""Detect anomalies using Interquartile Range."""
arr = np.array(values, dtype=float)
q1 = np.percentile(arr, 25)
q3 = np.percentile(arr, 75)
iqr = q3 - q1
lower_bound = q1 - multiplier * iqr
upper_bound = q3 + multiplier * iqr
anomalies = []
for i, val in enumerate(arr):
if val < lower_bound or val > upper_bound:
severity = "CRITICAL" if (
val < q1 - 3 * iqr or val > q3 + 3 * iqr
) else "WARNING"
anomalies.append({
"index": i,
"value": val,
"lower_bound": round(lower_bound, 2),
"upper_bound": round(upper_bound, 2),
"severity": severity,
"direction": "spike" if val > upper_bound else "drop",
})
return anomalies
Spend Pacing Monitor
from datetime import datetime
def check_spend_pacing(
hourly_spend: List[float],
daily_budget: float,
current_hour: int,
) -> dict:
"""Check if spend is pacing ahead of budget."""
total_spent = sum(hourly_spend)
expected_fraction = current_hour / 24.0
expected_spend = daily_budget * expected_fraction
pacing_ratio = total_spent / expected_spend if expected_spend > 0 else 0
projected_daily = (total_spent / current_hour) * 24 if current_hour > 0 else 0
alert = None
if pacing_ratio > 2.0:
alert = "CRITICAL"
elif pacing_ratio > 1.5:
alert = "WARNING"
return {
"total_spent": round(total_spent, 2),
"daily_budget": daily_budget,
"current_hour": current_hour,
"pacing_ratio": round(pacing_ratio, 2),
"projected_daily_spend": round(projected_daily, 2),
"over_budget_projected": projected_daily > daily_budget,
"alert": alert,
}
Composite Anomaly Scorer
def composite_anomaly_score(
spend_z: float,
ctr_z: float,
cvr_z: float,
cpc_z: float,
weights: dict = None,
) -> dict:
"""Combine multiple Z-scores into a single anomaly confidence score."""
if weights is None:
weights = {"spend": 0.3, "ctr": 0.25, "cvr": 0.25, "cpc": 0.2}
scores = {
"spend": abs(spend_z),
"ctr": abs(ctr_z),
"cvr": abs(cvr_z),
"cpc": abs(cpc_z),
}
weighted_score = sum(scores[k] * weights[k] for k in scores)
if weighted_score >= 3.0:
severity = "CRITICAL"
elif weighted_score >= 2.0:
severity = "WARNING"
elif weighted_score >= 1.5:
severity = "INFO"
else:
severity = "NORMAL"
top_contributor = max(scores, key=scores.get)
return {
"composite_score": round(weighted_score, 2),
"severity": severity,
"top_contributor": top_contributor,
"individual_scores": {k: round(v, 2) for k, v in scores.items()},
}
Examples
Example 1: Detect a budget runaway
User: "My Google Ads spend seems way higher than normal today."
Agent workflow:
1. Pull hourly spend data for last 7 days via GAQL
2. Run Z-score detection on today's hourly spend vs 7-day rolling average
3. Result: Hour 14 spend = $847, mean = $210, Z = 3.04 โ CRITICAL
4. Check pacing: 65% of daily budget spent by hour 14 (58% expected) โ WARNING
5. Recommend: Review search terms for irrelevant traffic, check if bid strategy changed
Example 2: CTR drop investigation
User: "Our display CTR dropped significantly this week."
Agent workflow:
1. Pull daily CTR for last 30 days
2. Run IQR detection: Q1=0.35%, Q3=0.52%, IQR=0.17%
3. Lower bound = 0.35% - 0.255% = 0.095%
4. This week's CTR: 0.08% โ Below lower bound โ ANOMALY
5. Cross-check: ad disapprovals? creative fatigue? placement changes?
6. Recommend: Refresh creatives, check placement reports, review audience overlap
Example 3: Multi-metric composite alert
User: "Set up anomaly detection for my top 5 campaigns."
Agent workflow:
1. Pull 30 days of spend, CTR, CVR, CPC for each campaign
2. Compute rolling baselines per campaign
3. Daily monitoring: compute composite anomaly score
4. Campaign "Brand - Search": composite = 1.2 โ NORMAL
5. Campaign "Competitor - Display": composite = 2.8 โ WARNING
- Top contributor: CVR (Z = -3.1, dropped from 2.1% to 0.4%)
6. Alert user with campaign name, severity, and top contributing metric
About this skill
Part of the Synter free skills collection โ open-source agent skills for advertising, PPC, and marketing automation.
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