BuySI

About BuySI

What is this?

BuySI is a free, public dashboard that tracks the real estate market across Staten Island's neighborhoods. Instead of looking at borough-wide averages that mask significant local variation, we break down the data by the 16 Neighborhood Tabulation Areas (NTAs) defined by the NYC Department of City Planning.

The goal is to give homebuyers a clear, data-driven picture of what's happening in the specific neighborhoods they're considering — not just prices, but market dynamics like how fast homes sell, whether they go over asking, and the overall balance between supply and demand.

Data Sources

Redfin Data Center

Primary source for market metrics: median sale price, days on market, inventory, sale-to-list ratio, and more. Redfin publishes bulk data files weekly (Wednesdays) and monthly at both neighborhood and zip code granularity. We map Redfin's 46 Staten Island neighborhood names to the 16 NTA boundaries, combining data via weighted averages when multiple Redfin neighborhoods fall within one NTA.

NYC Department of Finance — Rolling Property Sales

Individual transaction records for every property sale in Staten Island, including sale price, date, building class, and square footage. Used for property type breakdowns, price-per- square-foot analysis, and data confidence metrics (sample sizes and recency). Non-arm's-length transactions ($0 and $1 sales) are filtered out.

U.S. Census — American Community Survey (via NYC DCP)

Demographic and housing data: population, median household income, owner/renter ratios, housing stock types, and vacancy rates. NYC Department of City Planning publishes pre-tabulated ACS estimates by NTA, which aligns directly with our neighborhood boundaries. Updated annually.

NYC Department of Buildings — Permit Issuance

Active building permits and recent construction projects, showing the development pipeline in each neighborhood.

Market Temperature Score

The Market Temperature is a composite score from 0 (extreme buyer's market) to 100 (extreme seller's market). It combines five indicators with the following weights:

  • Months of Supply (25%)— Inventory divided by monthly sales. Below 4 months signals a seller's market.
  • Sale-to-List Ratio (25%) — How close to (or above) asking price homes sell for. Above 100% means competitive bidding.
  • Days on Market Trend (20%) — Whether homes are selling faster or slower than the prior period.
  • Percent Selling Over Asking (15%) — The share of sales that close above list price.
  • Price Reduction Rate (15%) — The share of listings with price cuts, indicating seller urgency.

Scores above 65 are labeled "Seller's Market," 35–65 are "Balanced," and below 35 are "Buyer's Market."

Update Schedule

Market data refreshes weekly, every Thursday. Redfin publishes updated bulk data on Wednesdays, and our automated pipeline processes it the following day. Census demographic data refreshes annually. The "Data updated" timestamp on the dashboard shows when the most recent data was processed.

Neighborhoods & Boundaries

We use the 2020 Neighborhood Tabulation Areas (NTAs) defined by NYC Department of City Planning. These aggregate census tracts into recognizable community names. Staten Island has 16 residential NTAs, which we group into three regions:

  • North Shore (7) — St. George, Stapleton, Rosebank, West Brighton, Westerleigh, Port Richmond, Mariners Harbor
  • Mid-Island (4) — Grasmere/South Beach, New Dorp, Todt Hill, New Springville
  • South Shore (5) — Oakwood, Great Kills, Arden Heights, Annadale/Huguenot, Tottenville

Some NTAs combine smaller neighborhoods — for example, "Todt Hill / Emerson Hill / Lighthouse Hill" is a single NTA. When multiple Redfin sub-neighborhoods map to one NTA, their metrics are combined using weighted averages based on transaction volume.

Known Limitations

  • Data lag — Redfin data reflects closed sales and may lag the current market by 2–4 weeks. NYC DOF rolling sales have additional processing delays.
  • Low-volume neighborhoods — Some neighborhoods have few transactions per month. Metrics based on small samples (under 5 sales) are flagged with a confidence indicator.
  • NTA boundary approximations— NTA boundaries don't perfectly match how everyone defines their neighborhood. Some properties near boundaries may be counted in the adjacent NTA.
  • Not a listing site — This dashboard shows market trends and analytics. It does not display individual property listings or facilitate property searches.

Data Confidence Indicators

When a metric is based on fewer than 5 transactions or the most recent sale is over 90 days old, an amber badge appears next to the value. This helps you judge whether a number reflects a robust trend or a thin data point.