Methodology
How ROSTER scores artists
Every score on a ROSTER artist profile is derived from verified platform API data — no estimates, no manual entries. Here's exactly how the numbers are calculated.
The three scores
Reach
0 – 100
Cross-platform audience size, log-scaled and market-weighted. 70+ = regionally established.
Momentum
−100 to +100
Rate of recent growth relative to current base. Positive = growing, negative = declining.
Engagement
0 – 100
How actively audiences consume content. Compares plays and views to follower counts.
Data sources
Spotify
Follower counts, monthly listener estimates via Web API
Audiomack
Plays, followers, and verified streams via partner API
YouTube
Subscriber counts and view totals via Data API v3
All data is fetched on a scheduled cadence and stored as timestamped snapshots. The snapshot date shown on each profile indicates when the numbers were last collected.
Frequently asked questions
Where does ROSTER get its data?
ROSTER pulls data directly from platform public APIs — Spotify for follower counts and monthly listener estimates, Audiomack for plays and followers, YouTube for subscriber and view counts. Data is fetched on a scheduled cadence and stored as timestamped snapshots so trends are trackable over time.
What is the Reach score?
Reach measures an artist's total cross-platform audience size, normalised to a 0–100 scale. Raw follower and listener counts are log-scaled (large numbers don't dominate unfairly), then weighted by platform significance in the artist's primary market. A score of 70+ indicates a regionally established artist; 50+ is solidly emerging.
What is the Momentum score?
Momentum measures the rate of growth over recent snapshots, ranging from −100 (declining fast) to +100 (growing fast). It compares the two most recent data points and normalises the change relative to the artist's current base. An artist with 10,000 followers growing to 12,000 scores higher than one with 1,000,000 growing to 1,001,000.
What is the Engagement score?
Engagement measures how actively audiences interact with an artist's content. It uses play-to-follower ratios from Audiomack, view-to-subscriber ratios from YouTube, and monthly listener density on Spotify. A high Engagement score means the audience is actively consuming, not just passively following.
How often is data updated?
Snapshots are collected automatically via scheduled cron jobs. The frequency varies by platform API limits — typically daily for Spotify stats and every 2–3 days for Audiomack and YouTube. The snapshot date is shown on every public profile.
Is this data verified?
ROSTER fetches directly from official platform APIs using credentials obtained through each platform's developer program. We do not scrape, estimate, or accept manual submissions from artists. The data is only as accurate as what each platform exposes through its API.
How is market weighting applied?
An artist's primary country (set on their profile) determines which platforms are weighted most heavily. For South African artists, Audiomack and Spotify are weighted higher because they represent the dominant listening surfaces in the market. For West African artists, Audiomack weight increases further. This prevents unfair comparisons between artists on different platform ecosystems.
Can artists manipulate their scores?
Scores are derived purely from API data — ROSTER has no mechanism for artists or managers to submit or adjust numbers. Bot followers and purchased streams would need to successfully fool the platform's own detection systems before they appear in our data, and even then, the Engagement score would reveal the inconsistency (high followers, abnormally low plays).