Methodology
Data Sources
This dashboard displays rental housing data from the Arboreal managed portfolio across the Seattle metropolitan area. Data is collected monthly from participating properties and reflects the characteristics of professionally-managed multifamily housing.
Important: This data represents a sample from the Arboreal managed portfolio, not the full Seattle rental market. Results may not be representative of all rental housing in the region.
Unit Population
The dataset includes only stabilized, revenue-generating units. This means:
- Units that have completed initial lease-up
- Units actively generating rental income
- Excludes units under major renovation or temporarily offline
- Excludes employee units, model units, and non-revenue units
Coverage
The dataset covers 20 districts across Seattle:
Unit classifications tracked include 11 categories:
Data Suppression
Some data slices are suppressed server-side when sample sizes are too small to report reliably. When data is suppressed:
- Charts will display "No data" for affected segments
- Bars will appear dimmed in bar charts
- Trend lines may have gaps for suppressed periods
Suppression protects against unreliable statistics from thin cohorts and helps maintain data quality across all views.
Rent Index Methodology
The Rent Index is an overlap-units chained index that tracks rent changes over time. This methodology:
- Compares rents only for units that appear in consecutive months ("overlap units")
- Calculates month-over-month growth factors from these matched pairs
- Chains growth factors together to form a continuous index
- Base value of 100 represents the starting period
This approach measures rent change, not rent levels. It controls for composition effects when new units enter or exit the sample, providing a cleaner measure of same-unit rent growth.
An index value of 108.5 indicates rents have increased 8.5% since the base period for the same set of units.
Vacancy Rate
Vacancy rate is calculated as the percentage of stabilized units that are unoccupied at the end of each month. This includes:
- Units available for rent and not under a current lease
- Units vacant due to tenant turnover
- Units undergoing make-ready between tenants
The vacancy rate is derived from occupancy data (vacancy = 1 - occupancy rate) for the stabilized unit population.
Delinquency Rate
The delinquency rate measures the percentage of units with an outstanding balance greater than $100 at end-of-month.
- Threshold: Balance due exceeds $100
- Timing: Measured on the last day of each calendar month
- Denominator: All stabilized, revenue-generating units
This metric serves as an indicator of tenant payment patterns and potential collection issues within the managed portfolio.
Aggregation Methods
When aggregating across districts or unit classes:
- Rent, Vacancy, Delinquency: Weighted averages using unit counts to ensure larger segments contribute proportionally
- Rent Index: Weighted by overlap unit counts to reflect the contribution of matched pairs to the index
Month-over-month and year-over-year changes are calculated as percentage changes for rent and rent index metrics, and as basis point changes for vacancy and delinquency rates.
Known Limitations
- Sample bias: Data reflects only the Arboreal managed portfolio, which may differ from the broader Seattle rental market.
- Portfolio composition: Professionally-managed multifamily properties are overrepresented compared to small landlords and single-family rentals.
- Geographic concentration: Coverage varies by district based on portfolio distribution.
- Timing: Data reflects end-of-month snapshots and may not capture intra-month fluctuations.
- Suppressed data: Some district/unit class combinations may be unavailable due to sample size requirements.