North Star Metric Skill: How to Define Input Metrics for Product Growth

The North Star Metric skill is a product-marketing framework that guides teams to select a single customer-centric KPI and define 3-5 actionable input metrics that drive it, using a structured workflow defined in the pm-marketing-growth package.

The North Star Metric skill is part of the open-source phuryn/pm-skills repository, designed to help product and growth teams align around a single measure of delivered value. Unlike lagging indicators like revenue, this skill focuses on identifying leading indicators that predict long-term success and the specific levers that move them.

What is the North Star Metric Skill?

The North Star Metric (NSM) skill lives in the pm-marketing-growth package and provides a systematic approach to metric selection. According to the skill definition in pm-marketing-growth/skills/north-star-metric/SKILL.md, the framework helps teams identify one core metric that captures the value your product delivers to users, supported by a small constellation of "input" metrics that explain how the NSM moves.

The skill validates the NSM against seven criteria for an effective metric and classifies the business context into one of three categories: Attention, Transaction, or Productivity. This classification ensures the metric aligns with the product's primary value proposition rather than vanity measures.

How to Define Input Metrics

Defining input metrics follows a five-step process outlined in pm-marketing-growth/commands/north-star.md. Input metrics are 3-5 "lever" metrics that directly drive the NSM and must be MECE (mutually exclusive, collectively exhaustive) according to the shared data model in pm-product-discovery/skills/metrics-dashboard/SKILL.md.

Step 1: Classify the Business Game

First, determine whether your product's primary value is Attention (engagement-driven), Transaction (marketplace or commerce), or Productivity (efficiency or output). This classification filters which metric types are appropriate for your specific business model.

Step 2: Generate NSM Candidates

Propose 2-3 potential North Star Metrics that represent leading indicators of user value. Examples include "Weekly Active Creators" or "Time Saved Per Session." Avoid lagging metrics like raw revenue or total sign-ups that don't reflect actual value delivery.

Step 3: Select the NSM

Evaluate candidates against the seven criteria and select the metric that best captures customer-centric value. The chosen NSM should be a leading indicator that predicts future business outcomes rather than a result of past activity.

Step 4: Define Input Metrics

For the selected NSM, identify 3-5 concrete, actionable drivers. Each input metric must include:

• Causal link: How it drives the NSM
• Owner: Team or individual responsible
• Current value: Baseline measurement
• Target: Specific goal

Step 5: Validate

Ensure the input metrics are MECE and that the NSM genuinely measures user value. The validation confirms that moving these inputs will predictably move the North Star Metric.

Internal Architecture and Source Files

The skill is implemented across several files in the phuryn/pm-skills repository:

• pm-marketing-growth/skills/north-star-metric/SKILL.md: Contains the core skill definition, including trigger phrases ("north star metric", "define north star"), and the step-by-step workflow.
• pm-marketing-growth/commands/north-star.md: Exposes the skill via the /north-star CLI-style command used by the Claude plugin system.
• pm-product-discovery/skills/metrics-dashboard/SKILL.md: Provides the shared data model for NSM, input metrics, and health metrics, ensuring consistency across discovery and growth teams.

Usage Examples

Invoke the skill using the command interface:

/north-star

The skill responds with a structured workflow:

> I’m going to help you pick a North Star Metric and three supporting input metrics.
> 1️⃣ **Classify the business game** – Are you building an attention‑driven app, a transaction platform, or a productivity tool?
> 2️⃣ **NSM candidates** – e.g., “Weekly active creators”, “Monthly revenue‑per‑user”, “Time saved per session”.
> 3️⃣ **Select the NSM** – “Weekly active creators” (captures value delivered to creators).
> 4️⃣ **Input metrics**  
> | Input Metric | Drives NSM By | Owner | Current | Target |  
> |--------------|--------------|-------|---------|--------|  
> | New creator sign‑ups | ↑ weekly active creators | Growth | 1 200 /mo | 1 800 /mo |  
> | Creator content uploads | ↑ weekly active creators | Product | 3 000 /mo | 4 500 /mo |  
> | Retention (30‑day) | ↑ weekly active creators | Ops | 45 % | 55 % |

To focus specifically on input metrics after selecting an NSM:

/north-star input-metrics

This generates actionable levers with ownership and targets:

> Based on the selected NSM “Weekly active creators”, here are three actionable input metrics:
> • **New creator sign‑ups** – the funnel entry point; increase acquisition spend.
> • **Creator content uploads** – the amount of value creators add; improve onboarding flow.
> • **30‑day retention** – keeps creators engaged; refine product‑led growth loops.

Summary

• The North Star Metric skill provides a structured framework for selecting a single customer-centric KPI that drives business success.
• Input metrics must be MECE (mutually exclusive, collectively exhaustive) and limited to 3-5 actionable drivers.
• The workflow involves classifying the business game, generating candidates, selecting the NSM, defining inputs with owners and targets, and validating the structure.
• Implementation resides in pm-marketing-growth/skills/north-star-metric/SKILL.md and is accessed via the /north-star command.

Frequently Asked Questions

What is the difference between a North Star Metric and input metrics?

The North Star Metric is a single leading indicator representing the core value delivered to users, while input metrics are the 3-5 actionable levers that directly drive changes in the NSM. As defined in pm-product-strategy/skills/product-strategy/SKILL.md, the NSM captures customer value, whereas input metrics explain the mechanics of how that value scales.

How many input metrics should I define?

The skill recommends defining 3-5 input metrics according to the specification in pm-marketing-growth/skills/north-star-metric/SKILL.md. This constraint ensures focus on the most impactful levers without overwhelming the team with too many variables.

What does MECE mean in the context of input metrics?

MECE stands for Mutually Exclusive, Collectively Exhaustive. This principle, referenced in pm-product-discovery/skills/metrics-dashboard/SKILL.md, means input metrics should not overlap (mutually exclusive) but together should cover all major drivers of the NSM (collectively exhaustive), ensuring clear ownership and no gaps in measurement.

How do I validate my North Star Metric?

Validation requires checking the NSM against seven criteria for effective metrics and ensuring it measures true user value rather than vanity or lagging indicators. The skill prompts validation of input metrics to confirm they are MECE and that the causal links to the NSM are supported by data or strong logical reasoning.

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