October 22, 2018

Explaining the Components of Inventory Change Reports: An Interview with Dav Vandenbroucke

Components of Inventory Change

In this column, Dav Vandenbroucke, HUD Senior Economist, talks about the Components of Inventory Change (CINCH) reports.

What is the CINCH report?

CINCH is a report based on the American Housing Survey (AHS). AHS generally includes the same housing units in every survey, so we can examine how those individual housing units change. The CINCH report includes two sets of tables, one forward-looking and one backward-looking, which predominately focus on how housing units move in and out of the housing stock.

Using the forward-looking tables, we can see which housing units have disappeared and why. For example, a researcher could find out what happened to housing units that existed 2011, but not in 2013. Generally, in the period covered by the CINCH reports, most of the housing units will still be there, but some of the housing units will have been demolished or destroyed by disasters. The CINCH report classifies what happened to the housing units in that time period.

The backward-looking set of tables could help a researcher determine from where new housing units in 2013 came. Most of the housing stock in 2013 existed in 2011, but some of it is new construction, some of it was converted from non-residential uses, and so forth. So, the point of CINCH is to see what happened to the housing units during the specified period of time.

How often are the CINCH reports released?

The reports are generally released after every AHS data update, which means every two years. However, the reports are currently on hiatus. In 2015, for the first time since 1985, we drew an entirely new sample for the AHS. So the 2015 survey covers a different set of housing units than the 2013 survey, meaning that the data cannot be directly compared. Because of this change, the next CINCH report will be released after the 2017 AHS data are made available. The AHS data have already been collected.

How does the rental market dynamics report differ from the CINCH report?

The rental market dynamics report is kind of a specialized version of CINCH. It concentrates on just the rental stock, and it categorizes rental units on the basis of affordability. In other words, the units are classified based on how much income a household would need to afford that unit without spending more than 30% of income on housing. The rental market dynamics report uses up to seven broad household income classifications, from extremely low-income to extremely high-income, to examine how the affordability of the units changed over a two year period. It looks at whether the low-rent units became more expensive and the high-rent units became less expensive. The report can help researchers examine whether units gentrified or filtered. Of course, during that time period, some of the rental units will have moved to the owner market. The rental market dynamics report also allows researchers to look backwards and determine from where new affordable units came. So, the rental market dynamic report is similar to the CINCH report, but it concentrates on the affordability of rental housing.

CINCH data are also released concurrently with each of the reports. How can researchers use CINCH data to gain insight into the housing market?

The AHS is a very rich data set, so there is a lot of information that we collect about housing units that is not in the CINCH reports. The CINCH data set takes the information about housing units in both years covered by the report and provides it in a format that can be connected to the basic public use AHS files. So, if you have a particular interest in some aspect of CINCH data that isn't in the CINCH report, you can use the data set to create your own tables. It is important to remember that the survey data have to be weighted; you take the 60,000 or so housing units that are in the American Housing Survey and add weights so that you can get a number that is comparable to the entire housing stock, which is about 110 million units. It is tricky to weigh surveys when you have surveys from two different years and you want them to be consistent. So there is a special set of weights for the CINCH reports, and those weights are in the data set as well so that people don't have to do that work themselves.

Finally, when are the next CINCH and rental market dynamic reports expected to be released?

As I said earlier, these reports have been on hiatus because of the new survey samples. The 2017 AHS data have been collected, and the public use files were released in September 2018. A contractor produces the CINCH and rental market dynamics reports for us, and we are in the process of starting a new contract for that work. Once we select a contractor, the contractor will begin work on the CINCH and rental market dynamic reports. So, the reports for '15 to '17 should be done by the end of 2019.

 
 
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