Asking prices and selling prices - a comparison that points to new metric

by Alistair Helm in


I read with interest a joint report by Realestate.co.nz and REINZ (published last week)  “New Zealand Property Report – asking & selling prices - a comparison”. The report states that based on analysis of property sales and property listings in the second half of last year – the median absolute difference between asking price and selling price was 2.67% nationally. That would mean that based on the most recent median sale price of $550,000 the median difference was just $15,000. Clearly indicating a very accurate estimate by agents of likely selling prices.

The report published this chart of asking price to sale price tracking the past 5 years.

I must confess for a couple of minutes I was somewhat confused, as I made the mistake of assuming that what this report had done was to track the monthly asking price as reported by Realestate.co.nz in their monthly NZ Property Report and the monthly REINZ median sale price. The chart for this set of data looks somewhat different as you can see.

The variance of national asking prices vs national sale prices is more like $100,000 as opposed to $15,000. This amounts to a 20% variance as opposed to the reports 2.67%. I then read a bit deeper into the report to understand why I had been confused and thereby explain the significant difference between these two seemingly similar data sets.

This new detailed joint report is based on the relationship between asking price and sales price where a price has been displayed when the property is listed for sale. So the data comprises just those listings where the property has been marketed with a price by the listing agent, thereby excluding all listings by auction, tender, or simply those for which no price is displayed.

Out of interest based on the current portfolio of all listings on the market at this time – the sample set in the report of properties where a price has been displayed when the property is listed for sale is by far the largest subset of properties on the market amounting to 61% of all listings. Some 16,877 from among the 27,643 properties on the market. This data is very helpfully provided on the Realestate.co.nz website under the Advanced Search on the Classic site – unfortunately another weakness of the proposed new website which has no such Advanced Search function.

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Being an analytical person, I began to wonder what this data point of median absolute difference between asking price and selling price was? – was it the amount of the variance of the median asking price to the median sales price for all the listings over that 6 month period? Or was it the median of all the variances between the asking price and selling of all the listings over that 6 month period?

I hope I have not confused you yet!

To hopefully help explain, here are a random set of fictitious data point to help explain my questioning:

comparison_asking_price_to_sales_price_REINZ_Realesatate.png

These 7 properties represent a fairly wide range of prices. The median asking price is $650,000 and the median sale price is $635,000 which relate to property #3. In choosing this fictitious group of 7 properties I have reflected sale prices that are both above and below the advertised price as I assume the listings that feature a price include both those with a price, as well as listings that feature the prefix of “offers over $xx / Buyer interest form $xx / Buyer enquiry over $xx”.

However as you will see the median absolute variance of this data set of 7 properties is not the ($15,000) from property #3 but is ($5,000) from property #4 – with positive and negative variances the median gravitates to a midpoint which in this case is close to zero especially as the extremes of variances are $70,000 below and $55,000 above asking price.

I therefore have to ask – is the use of median absolute variance appropriate?

An alternative data analysis could be to use the mean as opposed to the median. As detailed below the mean asking price to sales price for the same set of properties is $12,000 representing a 1.3% variance as opposed to the 0.9% of the median absolute variance.

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Aside from this question I have with the data point chosen for the analysis, I commend Realestate.co.nz and REINZ for this report. The takeaway is that where properties are marketed with a price; the price chosen at the recommendation of the listing agent is likely to be a very close approximation to the likely value of the property at the time of sale. This is valuable for buyers who often feel they are in the dark regarding prospective value of properties.

As a proposal for these two organisations I would like to recommend an extension of this one-off report. I feel it would be of significant value if Realestate.co.nz started to report this new metric of asking price for new listings that are marketed with a price. Tracking this by region by month as well as backdating data to 2007 would be really valuable extension to the NZ Property Report!