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Building Real Estate Price and Activity Indexes from Transaction Data

Article Quant Q&A · Author: Krish

Summary

The discussion explains how to think about constructing property indexes from transaction records and comparing them with a broad equity benchmark. It recommends deciding what each field measures: dates support time aggregation and seasonality analysis; sale amounts can help distinguish market segments; property type and state allow subgroup comparisons; and repeated investor identifiers may help separate occasional buyers from more active investors.

A quarterly moving average of transaction counts can reveal changes in market activity, but it is not necessarily a price index. The discussion encourages defining what an index is intended to represent and consulting established housing-index methodologies or replicating a published index with attribution. It does not give a specific formula, address adjustments for differences in property quality or mix, or establish that dividing cumulative amounts by a constant makes the result comparable to the S&P 500. The suggestions are exploratory guidance for a student project, not a validated index methodology.

Key ideas

  • A transaction-count moving average measures activity and does not by itself define a property price index.
  • Choose fields and aggregation methods according to the market feature the index should represent.
  • Property type and location can support separate market comparisons.
  • Repeated investor identifiers may help distinguish one-time buyers from more active investors.
  • A custom index should be compared with established methodologies and its sources credited.

Tags

Full text
# Real Estate Index in Python


# Real Estate Index in Python












I am trying to find a way to create Real Estate Index using Python 3.6 for my high school project. I have a csv file with the following columns:

- Date of Sale

- Amount

- Type (Commercial/Residential/Industrial)

- State

- Number of Investor

I want to create an index for each of the different types of properties, and then also compare it to the S&P 500, using data since about 2005.

- I have been learning from Python for Finance by Yves Hilpisch, but cannot find mention of creating a custom index.

- So far, I created a moving average of quarterly transactions, and it does show a very good visual and a near complete slowdown between 2007 to 2010. But is that a real index?

- My Y-Axis is in the Millions, but I would like it to be a much smaller number like the S&P 500. Can I just divide all cumulative figures by 10^6?

Could someone point me to some good (and free since my allowance is small) resource to learn about this?

Thank you so much.

## Answer by python_enthusiast (score 3)

https://quant.stackexchange.com/a/35825

I suppose you don't have to constrain yourself to that specific data, so you could refer to the Census Bureau if you need more data. Moreover, you can search on Google for ''housing index methodology'' if you want references on how to build professional indexes. Personally, I think it would be great practice to replicate an index for your high-school project (remember to state in your work that it is not an original idea and to quote the sources). However, your teacher might think it is better that you come up with something yourself, even if not so elaborate. In that case, I would suggest you think about the following:

1) Which variables are useful, and for what they are used. Here are some guidelines:

- date: to see the evolution in time, but also allows you to aggregate by period and see: if you have seasonality, if the annual/quarterly count of transactions has increased or decreased, the time between transactions, etc.

- amount: by the amount, you can cathegorize within the three categories that you already have and possibly distinguish whether the real estate being bought/sold is cheap or luxury (this is a good indicator of the state of the economy)

- type: compare with indexes related to each one (confidence indexes, activity indexes, etc)

- state: some regions are more industrial, while others are more residential. Your index could indicate the market evolution in each state by pointing out the evolution of activity for each of the three categories;

- number of investor: some investors buy one house to live in and that is it, while others might do this as a business. If a number only appears once in the dataset, you probably have the first case, while if it appears many times you are probably facing an institutional investor.

2) An index should give you a quick assessment of the market over time. You should be able to compare two moments and tell whether the market is better or worse (should you invest in it or not), but you might also want to build something that gives more details on the market that you are observing.

Shown in full with attribution under the source's licence. Licence: CC BY-SA 4.0 (Stack Exchange)

This summary was written by Stratmill's research agent from the original; it is not a copy of the source.