When should I use people as a metric in a Success Measurement case?

Metrics can focus on actions or people. Which is better?

When I work with candidates on success measurement interview cases, I often encounter two types of metrics: action-based metrics, like the total number of content views per day, and people-based metrics, like the total number of viewers per day. Both sound similar, but these two approaches provide vastly different insights into product health and engagement.

Take the case of Laura, a candidate preparing for a product management role at a well-known tech company. Laura’s task was to evaluate the success of a video-sharing platform, and she instinctively proposed measuring success by tracking unique viewers per day. “It’s logical,” she reasoned. “We want more people viewing our content, so more unique viewers means we’re growing!”

But here’s the twist. When I asked her to consider engagement, her answer revealed the core of the challenge with people-based metrics. Unique viewers could only show us that people came, not that they stayed engaged. Unique viewers don’t capture repeat behavior—whether users are watching multiple videos or even finishing one.

What Makes These Metrics So Different?

Let’s give these metrics clear names that reflect what they really are. Total number of content views per day is Total Views. Total number of viewers per day is Unique Viewers. Now, let’s see how they differ.

Magnitude

Total Views captures every single instance of viewing. So, if one person watches a video multiple times, each view is counted separately.

Unique Viewers counts only the individuals, regardless of how many times they’ve watched the content. This metric is inherently capped by your user base size.

Variability

Total Views tends to be more dynamic. As users engage differently each day, this metric reflects those fluctuations and provides a real-time pulse on engagement.

Unique Viewers remains more stable, providing a general sense of reach but missing depth on repeated interactions.

Data Type

Total Views is a count of actions. It shows how users are interacting with the content repeatedly, making it ideal for tracking active engagement.

Unique Viewers is a count of individuals. It indicates how many distinct people are accessing your content, which is useful for gauging reach and retention but doesn’t offer as much depth on interaction intensity.

Why the Distinction Matters: Avoiding Metric Misalignment

Using these metrics interchangeably can mislead product insights and seriously trip you up during a case interview. Here’s how each should be used correctly:

People-Based Metrics for Acquisition and Retention:

Metrics counting unique people are most useful when you’re tracking how well you’re acquiring and retaining users. For instance, if you want to know how many people are coming back to your product, a unique viewer count will be more relevant than a view count. Retention is inherently about keeping individual users, making people-based metrics ideal.

Action-Based Metrics for Engagement

Actions, like views, clicks, or shares, provide insight into engagement—how users are interacting with the product. Engagement is behavior-driven and requires a metric that can capture repeated actions. Tracking these activities helps you understand the intensity and quality of interactions, which is key to measuring user satisfaction and product stickiness.

Practical Examples: When to Use Each Metric

Consider a platform like Instagram Reels. Suppose your goal is to understand the success of a new feature in increasing viewership.

Using “Total Views” would reveal how often the reels are watched, giving insights into engagement. For instance, if each reel is being watched multiple times, it signals deep interaction with the content. If engagement is a core priority, this metric will best reflect it.

Using “Unique Viewers” shows how many different users are viewing the reels, which is more useful for reach and acquisition goals. If you’re trying to grow the user base, you’ll want to know how many new viewers each reel is attracting.

For a holistic view, it’s often beneficial to use both types together to paint a full picture—unique viewers for reach and total views for engagement. Each offers a piece of the success puzzle, but using them in the right context ensures a balanced understanding of user behavior.

By aligning your metrics with your goals, you ensure that you’re gathering the most relevant insights, leading to better-informed decisions and a clearer view of product success.