How we score
Reviews are weighted by what research shows actually affects tenant health. Conditions with documented health impacts count more than cosmetic complaints. The methodology is adapted from three validated public health instruments and the weights come from peer-reviewed evidence.
Foundation
Where the items come from
Our 27-item assessment is adapted from three validated public health instruments:
Observational Housing Quality Scale (OHQS)
Developed by Krieger and Higgins to systematically assess housing conditions linked to health outcomes. We use it for the unit-level items: structural problems, pest infestation, moisture issues.
Krieger & Higgins (2002), American Journal of Public Health
Physical Housing Quality Scale (PHQS)
A comprehensive instrument for building-level housing quality, validated across diverse housing types and urban contexts. We use it for the building-level items: common areas, security, exterior, noise, mail, trash.
Jacobs et al. (2009), Environmental Health Perspectives
WHO LARES Study
A pan-European housing-and-health study, validated for evaluating landlord and management factors that affect tenant wellbeing. We use it for the landlord-level items: maintenance response, communication, professionalism, and rental practices.
Bonnefoy et al. (2003), American Journal of Public Health
Each of our 27 items traces to one of these three instruments.
The math
How scores are calculated
Each review collects ratings across 27 individual items organized into three domains:
Unit quality
10 items covering structural integrity, systems, and livability
Based on OHQS interior assessment domains
Building
9 items covering common areas, security, and amenities
Based on PHQS building-level indicators
Landlord
8 items covering responsiveness, communication, and practices
Based on WHO LARES management factors
We don't treat every item equally. Items with documented health impacts carry more weight in the score.
What we ask
The 27 rating items
Each item traces to one of the three instruments above. Items marked with * carry health and safety weighting. The review form also includes 5 questions that aren't scored: recommendation, tenure, move-out year, voucher acceptance, and street-lighting context.
Unit quality (10 items)
- * Structural integrity
- * Plumbing systems
- Electrical systems
- * Climate control (heat and AC)
- Ventilation
- * Pest control
- * Mold and moisture
- Appliances
- Layout and space
- Accuracy to listing
Source: OHQS
Building (9 items)
- Common areas
- * Security features
- Exterior condition
- Neighbor noise
- External noise
- Mail and package handling
- Laundry facilities
- Parking
- Trash and recycling
Source: PHQS
Landlord (8 items)
- Maintenance response
- Communication
- Professionalism
- Lease clarity
- Privacy respect
- Deposit handling
- Rent practices
- Non-retaliation
Source: WHO LARES
Why some items count more
Health and safety weighting
Some housing conditions have stronger associations with health outcomes than others. The weights below come from epidemiological research:
Pest control
Pest infestations (cockroaches, rodents, bed bugs) are strongly associated with asthma, allergic reactions, and disease transmission. Cockroach allergen is a major trigger for childhood asthma in urban environments.
Mold and moisture
Visible mold and dampness are associated with a 1.5-3.5x increased odds ratio for respiratory symptoms, including asthma, wheeze, and upper respiratory infections. This is one of the most well-documented housing-health relationships.
Structural integrity
Structural deficiencies including damaged floors, walls, and ceilings pose direct injury risks from falls, collapses, and accidents. Poor structural condition also often indicates deferred maintenance affecting other systems.
Climate control (heating and cooling)
Inadequate heating is associated with cardiovascular stress, hypothermia risk, and respiratory illness. This is particularly important in Boston's climate where winter temperatures regularly drop below freezing.
Plumbing
Plumbing issues create pathways to mold growth through water damage and leaks. Persistent moisture from plumbing problems is a primary cause of indoor mold, creating indirect health effects.
Security
Building security features (working locks, secure entry, lighting) directly impact personal safety and are associated with reduced risk of break-ins, assault, and psychological stress from fear of crime.
A worked example
How weighting changes a score
The weights only matter if you can see what they do. We'll start with a made-up unit to show the formula, then run the exact same math on two real reviews.
A made-up unit
Picture a place that looks fine on a tour but hides real problems. Here are eight of its unit-level items, each rated 1 to 5. The health and safety items carry extra weight, so the last column shows each rating multiplied by its weight.
| Item | Rating | Weight | Rating × weight |
|---|---|---|---|
| Mold and moisture | 1/5 | 1.5× | 1.5 |
| Pest control | 1/5 | 1.5× | 1.5 |
| Structural integrity | 5/5 | 1.3× | 6.5 |
| Climate control | 2/5 | 1.3× | 2.6 |
| Plumbing | 5/5 | 1.2× | 6.0 |
| Electrical systems | 5/5 | 1.0× | 5.0 |
| Appliances | 5/5 | 1.0× | 5.0 |
| Accuracy to listing | 5/5 | 1.0× | 5.0 |
| Totals | 29 | 9.8 | 33.1 |
Same eight ratings, averaged two ways using the totals from the table:
Standard
sum of the ratings ÷ number of items
29 ÷ 8
Health-weighted
sum of (rating × weight) ÷ total weight
33.1 ÷ 9.8
Standard average
Every item counts the same.
Our health-weighted score
Health and safety items count for more.
What the shift means
Flat, this unit scores 3.6. The way we score it, 3.4. That 0.2-star difference sits right on the mold, pest, and climate problems. The weighting leans the score toward the conditions that affect a tenant's health.
The same math on real reviews
That unit is made up, and made-up numbers are easy to rig. So here's the same calculation on two real reviews, scored both ways. The per-item ratings don't change between the columns; only the way they're combined does.
38 Edgemere Road
2 bedrooms · real review, address changed for privacy| Domain | Flat average | How we score it |
|---|---|---|
| Overall | 3.8 | 3.7 ▼ |
| Unit | 3.3 | 3.1 ▼ |
| Building | 4.1 | 4.1 |
| Landlord | 4.1 | 4.1 |
This unit rates well on the visible things. Plumbing, appliances, and layout were all 5 stars. But pests and mold were both rated 1, and those count 1.5x. The weighting pulls the unit score from 3.3 to 3.1 and the overall from 3.8 to 3.7, so an apartment that shows well on a tour doesn't get to hide its health problems.
70 Brookvale Road
2 bedrooms · real review, address changed for privacy| Domain | Flat average | How we score it |
|---|---|---|
| Overall | 3.9 | 3.9 |
| Unit | 3.8 | 3.9 ▲ |
| Building | 4.1 | 4.1 |
| Landlord | 3.7 | 3.7 |
This one goes the other way. Here pests and mold were both 5 stars, so the items that count most are the strong ones. The weighting nudges the unit score up from 3.8 to 3.9. It rewards a place that's solid where it matters; it doesn't only mark places down.
On a full review the shift is usually a fraction of a star, and that's deliberate. Only the health and safety items carry extra weight, and they're averaged in with everything else. The weighting leans a score toward what affects your health; it doesn't override the rest.
Reading the numbers
Interpreting scores
The color-coded scores in the examples above all come from the same four-band scale. Here's what each band means at a glance:
Treat a score as a starting point, not a verdict. Every review comes from a tenant's own experience, and we can't independently verify each one, so use your own judgment. The written reviews matter as much as the number, so read them alongside it; they carry the context a score can't.
Recent reviews count more
Recency weighting
Aggregate scores apply recency weighting because buildings and management change over time. Newer reviews count more than older ones, but historical reviews still count.
| Review Age | Weight Applied |
|---|---|
| 0-2 years | 100% |
| 3 years | 95% |
| 4 years | 90% |
| 5+ years | 85% (floor) |
Sources
References
Survey instrument sources
- Krieger, J., & Higgins, D. L. (2002). Housing and health: Time again for public health action. American Journal of Public Health, 92(5), 758-768. Source for OHQS (Observational Housing Quality Scale) - Unit condition items doi:10.2105/AJPH.92.5.758
- Jacobs, D. E., Wilson, J., Dixon, S. L., Smith, J., & Evens, A. (2009). The relationship of housing and population health: A 30-year retrospective analysis. Environmental Health Perspectives, 117(4), 597-604. Source for PHQS (Physical Housing Quality Scale) - Building-level items doi:10.1289/ehp.0800086
- Bonnefoy, X., Braubach, M., Moissonnier, B., Monolbaev, K., & Röbbel, N. (2003). Housing and health in Europe: Preliminary results of a pan-European study. American Journal of Public Health, 93(9), 1559-1563. WHO LARES Study - Landlord/management assessment items doi:10.2105/AJPH.93.9.1559
Health and safety weighting evidence
- Krieger, J. (2010). Home is where the triggers are: Increasing asthma control by improving the home environment. Pediatric Allergy, Immunology, and Pulmonology, 23(2), 139-145. Evidence for pest/allergen weighting doi:10.1089/ped.2010.0022
- Fisk, W. J., Lei-Gomez, Q., & Mendell, M. J. (2007). Meta-analyses of the associations of respiratory health effects with dampness and mold in homes. Indoor Air, 17(4), 284-296. Evidence for mold/moisture weighting (OR 1.5-3.5) doi:10.1111/j.1600-0668.2007.00475.x
- WHO Regional Office for Europe. (2018). WHO Housing and Health Guidelines. World Health Organization. Comprehensive evidence review for housing-health relationships WHO Publication
Methodology references
- Hu, N., Pavlou, P. A., & Zhang, J. (2017). On self-selection biases in online product reviews. MIS Quarterly, 41(2), 449-471. Evidence for recency weighting in review aggregation doi:10.25300/MISQ/2017/41.2.06
Tenants are the experts
You know your home better than anyone who tours it for ten minutes. The full methodology is public, the weights come from cited research, and every review shows both its raw item ratings and its weighted scores. You can always check our work.
Have questions about our methodology?
Contact us