You Asked, We Fired Up Excel and Geeked Out Until We Had an Answer

In a comment on Your Mercer Island Real Estate Market Fix, Richard asked:

Sometime it would be interesting to look at the data by Mercer Island neighborhood (are some areas in decline?) and by price band. For example, if beachfront property continues to hold its value but the rest of the island is falling in price — that means something very different than the opposite situation, even though the medians are all the same.

As a secretly obsessed data junkie, I immediately took it upon myself to ignore my normal responsibilities of work and home and dig into the answer. Keith, who seems to have a wealth of data about real estate, suggested the Tax Assessor Records. Since Redfin brings tax records into its online application, and I’m more familiar with that application, I went straight to it.

I broke the data down by neighborhood, because a price band analysis might be confounded by the changing prices themselves. I do report averages of square footage and number of beds and baths so you can see how the inventory of sold houses changed in these periods.

The somewhat arbitrarily defined neighborhoods are:

  • North Mercer Island: North of SE 40th– 111 sales in the last year
  • Mid-Island: SE 40th to SE 58th St- 82 sales in the last year
  • South Mercer Island: South of SE 58th St- 112 sales in the last year

I downloaded recent sales in each of these areas over the last year and broke them down by quarter. I excluded condos– North Island was the only neighborhood that had condo sales– and excluded one home in Mid Island where the sale price wasn’t recorded. The average $ per square foot be neighborhood turns out as follows:

Price Per Square Foot, Mercer Island Neighborhoods
The results do show a lot of variation by neighborhood:

  • South Mercer Island has slid from $603 per square foot to $342 in the last three months; however, note that there were only 8 sales in the past three months versus 42 at 9-12 months ago. Also, the average home size was a little larger in the past three months, although the average # of bedrooms stayed constant at around 4.
  • North Mercer Island has seen a less dramatic slide, from $528 per square foot to $450. However, the average home sold in the last three months was smaller by over 1,000 square feet than homes sold 9-12 months ago- 2,436 vs. 3,524 sq. ft.
  • Mid Island saw a small increase in price per square foot over the year, from $414 to $452 per square foot. The average home sold got much larger, however, the opposite of the effect in the North Island.

So Richard, you were right: even though the overall median price for Mercer Island homes has fallen only a bit, there are big differences in price per square foot trends by neighborhood.

You can find full data by neighborhood in the charts at the end of this post.

Mercer Island Waterfront

Then, I took on the waterfront question. Using lot outlines, I found the 17 waterfront properties that sold in the last year. This is a small data set, so take the results with a big, crunchy grain of salt. In particular, only 2 properties sold in the last three months and only 3 sold between three and six months ago, so aggregate data for those periods is more than questionable. In any case, here’s the same chart, now with waterfront properties broken out separately (but not removed from their original neighborhood).

Prices, Mercer Island Neighborhoods and Waterfront

Summary by neighborhood

Here are all the summary stats by neighborhood, plus waterfront:

Details on North Mercer Island, South Mercer Island, Mid Island, and Waterfront

Caveat: I may have screwed something up in this analysis, though I tried not to. If you see something strange or have an opinion on these results, leave a comment.


7 responses to “You Asked, We Fired Up Excel and Geeked Out Until We Had an Answer

  1. Well…I prefer “source data” whenever possible.

    Looking at sales from 3/16/2007 through 3/15/2008 (recording tend to lag a few days, so this would give a complete year), the King County Assessor’s site says that there were actually 568 sales in that period, and 55 of those were “Lake Washington” waterfront.

    63 of the sales were in SubArea 1, 48 in 2, 129 in 3, 75 in 4, 83 in 5, 66 in 6, 104 in 7.

  2. A quick followup…when I queried for sales between $0 and $100, that actually filters out 209 sales (and 23 waterfront). So perhaps that Redfin data isn’t so far off after all.

  3. mercerislandblogger

    Thanks Keith. Yes, it shouldn’t be too far off. I didn’t mention this in the post, but I found waterfront simply by panning the map around and looking at where the past sales were. So it’s very possible that I missed a few, or that my definition of waterfront by visual inspection differed from the tax assessor’s.

  4. Very very cool! thanks for doing the calculations!

    My hunch is that MI property values will always be pretty secure, since a relatively high proportion of people basically “need” to live here for various reasons — family, schools, location, etc. — and don’t really shop in other neighborhoods. Although it’s hard to read much into a small amount of data over a short time period, your analysis tells me that the only thing that really changes is WHERE they end up living.

  5. Pingback: Mercer Island Bloggers: Now +1 « Surrounded By Water: A Mercer Island Blog

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