Member Months — the enrollment heartbeat

fct_member_month is the payer's periodic snapshot: one row per enrolled member per month. It answers the question a health plan lives on — how many members are covered, in what products, over time — and it is the denominator behind every per-member metric.

Enrolled members over time

Distinct members carrying coverage in each year — the enrollment curve rising as the synthetic population ages into the plan and tapering toward the present.

Coverage composition

What products those members are enrolled in, as a share of member-months over time.