Monday, May 6, 2013

Network analysis of Manhattan apartment buildings

Manhattan has been described as one of the most real estate obsessed neighborhoods on earth (after Monaco); and another thing it is especially obsessed about is prestige. So, a comparison of the most prestigious apartment (Co-operative and Condominium) buildings is of especial interest, I guess.

In Manhattan, prestige seems to result from such things as the building's overall architecture, the scale and layout of the apartments, the notoriety of its current and past residents, the sheer cost of buying any of the apartments, and the requirement that a purchaser be able to stomach the exorbitant monthly maintenance fees.

However, these are not readily quantifiable attributes, except for the monetary ones, which change from year to year.

CityRealty (a New York City apartment search and resource site) has addressed this conundrum by evaluating the best-known apartment buildings based on a consistent set of non-monetary criteria: CityRealty's New York City Condos & Co-ops. They note:
We rate each building based on its architecture, location and features, using the same scoring methods and criteria for all buildings. The maximum number of points for Architecture is 44, Location 36, and Features 39. However, it is virtually impossible for any building to get the full amount of points for any category.
There are 18 criteria for Architecture (each scoring 1-8 points), 14 criteria for Location (1-5 points), and 22 criteria for Features (1-5 points). CityRealty list 3,085 apartment buildings, but only 1,943 of them have ratings.

I have concerned myself only with those buildings that have ratings ≥ 88 (the ratings vary from 30–99), which is 95 buildings. These buildings differ very little in the top-scoring criteria, which is to be expected if they are considered to be the top-rated buildings. These criteria include: Distinction of exterior (8 points), Retail quality (5), Street ambience (5), Distance to business district (5), Distinction of lobby (5), and Number of units per floor (5).

However, these buildings do differ considerably on the other criteria, which include presence or absence of all sorts of  "desirable" characteristics, such as: gargoyles, illumination, water element, recreational roof, garage, maid's room, elevator person, and absence of external air conditioners. This makes a network analysis possible, which will summarize the similarities among the various buildings.

The analysis

I compiled a list of 57 of the buildings for analysis, including all of the top buildings as rated by CityRealty (37 buildings; scores 92–99), plus a selection of others (20 buildings; scores 88–91) that appear to be noteworthy as indicated by various internet lists (eg. based on architecture, prestige, history, cost of apartments). I then collated the data provided by CityRealty. (See the Postscript for a comment on the data.) There are 29 Co-operatives and 28 Condominiums in the analysis. However, two buildings have identical scores, because the Time Warner Center and the Mandarin Oriental are two towers in the same development — the apartments in the south tower have a One Central Park address (Time Warner Center) and those in the north tower are The Residences at the Mandarin Oriental.

As usual for my data analyses, I have compared the buildings based on what is (appropriately!) called the manhattan distance and then calculated a NeighborNet network. Buildings that are closely connected in the network are similar to each other based on the various criteria used by CityRealty, and those that are further apart are progressively more different from each other.

The network shows seven clusters, which I have color-coded. These clusters represent buildings that have many characteristics in common. Notably, these buildings are also clustered in space, as shown in the map below (also available on Google Maps), which is color-coded to match the network. (Note that yellow is a bit hard to represent in the network.) In particular, the colors occur as follows:
  • light blue – around the fringe of the Upper East Side
  • red – Upper East Side next to Central Park
  • yellow – along the west side of Central Park
  • pink – Upper West Side and south-west Central Park
  • purple – south-east corner of Central Park + 2 Upper East Side + 1 Financial District
  • blue – mostly around the southern and eastern sides of Central Park + 2 Midtown East + 1 Financial District
  • green – Downtown + 2 west of Central Park

The strong geographical clustering of the different types of buildings within Manhattan is not unexpected, since many of the areas were developed at the same time and in a similar architectural style. (This geographical result is not because of the importance of Location in the CityRealty scores, since most of the buildings score very well on all of the Location criteria, except Traffic noise). Important differentiating Architecture criteria include: presence of a Plaza or Atrium, Water Element, Illumination, Non Rectilinear Form, Ceiling Height, and Balconies.

There are also perceived differences in the desirability of the various areas, which means that nearby buildings often provide similar Features (such as Recreational Roof, Elevator Person, Maids Room, Garage, or Catering). This is further related to the non-random distribution of the two apartment types: all green are condominiums; all light blue and yellow are co-operatives; all except one of the red are co-ops; all except two of the blues are condos; and only the pink and purple are mixtures of the two types. Co-operative buildings tend to provide a range of more expensive features than do the condominiums (most of the co-ops are at the bottom-left of the network graph).

The purple group are all similar in ambience, in that they are buildings that include both a hotel and apartments (usually, the lower part is the hotel and the tower is a co-op or condo). The exception is the Cipriani building, which is part of a world-wide chain. The pink group were all built at a similar time (1902-1908, except the Dakota in 1882) and in a similarly opulent style, and they are now designated as historic landmarks.

CityRealty also provides lists of the Top 10 Most Prestigious Co-ops and the Top 10 Most Prestigious Condos. These are indicated with numbers and letters, respectively, in the network diagram. These buildings are somewhat clustered in the network, but it is clear that "prestige" is not directly related to the criteria used by CityRealty in their ratings (if it was, then the buildings would be much more clustered in the network). Furthermore, buildings such as River House are not necessarily as prestigious as they once were (see here and here), and so their places in these lists might be contested.

It is also worth noting that not all of the most expensive buildings are necessarily in the list analyzed. For example, in 2012 some very expensive apartments were also sold in the co-op buildings at 785 Fifth Avenue, 884 Fifth Avenue, and 1030 Fifth Avenue, which are not included in the network analysis.

Finally, not all of the apartment buildings discussed here are necessarily lived in by their owners, particularly those in condominium buildings. For example, the New York Times has noted:
In a large swath of the East Side bounded by Fifth and Park Avenues and East 49th and 70th Streets, about 30 percent of the more than 5,000 apartments are routinely vacant more than 10 months a year because their owners or renters have permanent homes elsewhere, according to the Census Bureau’s latest American Community Survey.
This is particularly true of the most expensive condo apartments:
Pieds-à-terre exist throughout the New York City condo market, a separate little world of vacation homes and investment properties. But the higher the price, the higher the concentration is likely to be of owners who spend only a few months, a few weeks or even just a few days each year in their apartments. This very costly form of desolation means that some of the city’s most expensive residential buildings stand mostly dark, lonesome and empty on the inside.

I should point out, in passing, that CityRealty have not been as consistent in their ratings as might be hoped. For example, they note that: "On occasion, we may add (or subtract) a few points based on our subjective view of the building, so if the numbers don't add up exactly as you expect, that's why." I have ignored these extra subjective points in my analysis.

What I have not been able to ignore is some of the other inconsistencies. For example, "The Collection" building stands out like a sore thumb in the Sutton Place area (it is glass while its near neighbors are brick), as does "40 Bond Street" (it is bright green while its neighbors are brick or stone). Nevertheless, CityRealty have coded them: "Contextual Design: No, but Very Good", and scored both buildings 3 out of 3 on this criterion. Clearly, this confounds two criteria, Distinction of Exterior and Contextual Design, as CityRealty are allowing their claim that each building is an "Architectural Masterpiece" (and thus they score 8 out of 8 on Distinction of Exterior) to cloud their decision about whether each building also has "Contextual Design" (where CityRealty admit that each building should score 0 out of 3). Even more oddly, they also code "The Gainsborough" building exactly the same way ("Contextual Design: No, but Very Good") and yet, in the photo they show, this building seems to fit perfectly into its context. Indeed, "The Collection" might also fit in, if it was in a more modern location than Sutton Place, but there seems to be no such hope for "40 Bond Street".


  1. That's a very in-depth analysis David. One does wonder while touring around these residential areas in Manhattan if they really looked carefully at the blueprints of these condos and apartment buildings and compared it to the existing neighborhood theme before approving the design. Seems like the desire of the developers to make their properties stand out from the rest still prevails. Neighborhood theme be damned.

  2. Seems like the desire of the developers to make their properties stand out from the rest still prevails. Neighborhood theme be damned.
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