Case-Shiller U.S. National Home Price NSA Index Definition

What Is the S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index?

The S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index measures the change in the value of the U.S. residential housing market by tracking the purchase prices of single-family homes. The index is compiled and published monthly.

The national index is widely viewed as a barometer of the U.S. housing market and the broader economy. In media reports, it is often called simply the Case-Shiller Home Price Index.

The national index is one of three related Case-Shiller indices. The two remaining indices are composite indices of housing prices of 10 cities in one and 20 cities in the other.

Understanding the S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index

The Case-Shiller Index was developed in the 1980s by three economists: Allan Weiss, Karl Case, and Robert Shiller. It is a widely used and respected barometer of the U.S. housing market and the broader economy.

The housing market and the overall economy are interlocked in many ways. When real estate prices go up, homeowners often feel more secure in their investments and are more confident in their spending. Developers invest more in building new houses—this increase in overall activity boosts gross domestic product (GDP).

Most American houses are owner-occupied; thus, housing price indexes can provide a gauge of how much money is circulating in the economy. The S&P CoreLogic Case-Shiller National Home Price Index, one of the most well-renowned measures of house valuations in the U.S., is closely monitored by economists and investors.

What the Index Tells You

The S&P CoreLogic Case-Shiller Indices measure the change in the value of the U.S. residential housing market by tracking the purchase prices of single-family homes but do not cover newly constructed houses, condominiums, and co-ops. 

There is a two-month time lag in the data reported, so a report issued in May includes sales through March. All prices are compared to their prices one year before; however, comparisons are shown for one month ago, three months ago, and year-to-date. Annualized changes over three years, five years, and 10 years also are published by S&P Global.

The Case-Shiller indices are perhaps the best-known trackers of residential property prices, but there are several alternatives that investors can use to track real estate valuation fluctuations. They include the Federal Housing Finance Agency's (FHFA) Housing Price Index (HPI), First American CoreLogic's LoanPerformance Home Price Index, and the IAS360 House Price Index. Each index differs in the criteria it uses.

The 3 S&P CoreLogic Case-Shiller National Home Price Indices

The S&P CoreLogic Case-Shiller National Home Price Index has two offshoots, published separately, that focus on home prices in major U.S. cities.

• The national home price index covers nine major census divisions and is calculated monthly using a 3-month moving average.
• The 10-city composite index covers Boston, Chicago, Denver, Las Vegas, Los Angeles, Miami, New York, San Diego, San Francisco, and Washington, DC. It is published on the last Tuesday of each month at 9 a.m. Eastern Time.
• The 20-city composite index includes all of the above cities, plus Atlanta, Charlotte, Cleveland, Dallas, Detroit, Minneapolis, Phoenix, Portland (Oregon), Seattle, and Tampa. It also is published on the last Tuesday of each month at 9 a.m. Eastern Time.

S&P CoreLogic Case-Shiller National Home Price Index Methodology

According to S&P CoreLogic, the indices are compiled using the following methodology:

• Repeat Sales Method: Each index measures changes in the prices of single-family detached residences using the repeat sales pricing technique.
• Index Approach: Indexes are based on observed changes in home prices and are designed to measure increases or decreases in the market value of residential real estate in 20 defined metropolitan statistical areas (MSAs) and three price tiers—low, middle, and high.
• Creation of Sales Pairs: The movement in the price of single-family homes is measured by collecting data on actual sale prices. When a home is resold, the new sale price is matched to its first sale price. These two data points are called a "sale pair," and the difference in the sale pair is measured and recorded. Sales pairs yield the price change for the same houses, keeping the quality and size of each house constant.
• The Weighting of Sales Pairs: The indexes are value-weighted and designed to control for the quality change in the homes being measured. Sales pairs are assigned weights to account for price fluctuations that can be attributed to factors such as extensive remodeling, an addition, or extreme neglect. Time intervals between sales are also considered.
• Three-Month Moving Average: Indexes are calculated monthly using a three-month moving average algorithm. Home sales pairs are accumulated in rolling three-month periods.

The Bottom Line

The S&P CoreLogic Case-Shiller U.S. National Home Price NSA Index measures the changes in the value of residential single-family homes in the U.S. It is one of the more popular housing market indicators used by investors and other parties to gauge opportunities in the market.