Showing posts with label New York. Show all posts
Showing posts with label New York. Show all posts

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.
Postscript

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".

Monday, March 25, 2013

Network analysis of New York neighborhoods


Trying to quantify the characteristics of a neighborhood is a tricky business. Part of the problem is trying to define the nebulous idea of "livability" with respect to a geographical area, and part is due to the impracticality of collecting most of the data that might allow us to quantify the various aspects of life in that area.

Nevertheless, in New York magazine Nate Silver had a go at this in 2010, by trying to identify The Most Livable Neighborhoods in New York. He tried this because:
there is a wealth of information to study. The Bloomberg administration gathers reams of data about almost every element of life in the city — from potholes to infant-mortality rates— as do New York University's Furman Center and the U.S. Census Bureau. Sites like Yelp provide a reasonably objective perspective on the popularity of neighborhood bars and restaurants. StreetEasy.com and Zillow.com publish the costs of apartment space per square foot. Ethnic diversity is now broken down in much finer gradients than black and white ... Our goal was to take advantage of this wealth of data and apply a little bit of science to the question. If there was anything that could plausibly affect one's quality of life in a particular neighborhood, we tried to incorporate it.
New York thus provides a unique opportunity to try quantifying the nedbulous, and I think that it is worth looking at these data in more detail.

The data

The data were compiled into twelve broad categories, representing different characteristics about the various New York neighborhoods:
 Affordability / Housing Cost (as measured on a price-per-square-foot basis, for both renters and buyers), Housing Quality (historic districts, code violations, cockroaches), Transit and Proximity (commute times to lower Manhattan and midtown, the density of subway coverage), Safety (as measured by violent- and nonviolent-crime rates), Public Schools (test scores and parent satisfaction), Shopping & Services (the number of neighborhood amenities, especially supermarkets), Food & Restaurants (judged by density and quality of options), Nightlife (ditto), Creative Capital (arts venues as well as the number of residents engaged in the arts), Diversity (in terms of both race and income), Green Space (park and waterfront access, street trees), and Health & Environment (noise, air quality, overall cleanliness).
The data were gathered from the stated sources, and are presented in the original magazine article for 50 of the 60 neighborhoods that were assessed. The data for all of the characteristics were then summed for each neighborhood, based on a particular weighting scheme for the 12 categories. This provided "a quantitative index of the 50 most satisfying places to live."

The sum total of the scores is not actually very different among the neighborhoods (score 73–78 / 100), and therefore the choice between them on that basis is (as the author admits) "splitting hairs". More particularly, neighborhoods with very different characteristics can end up with the same total score — they simply get that total by combining the category scores in very different ways (ie. the neighborhoods have different strengths and weaknesses).

So, this is a rather limited approach to assessing the data. Surely we can get more out of the data than this? What would be more useful is a picture showing which neighborhoods are similar to each other based on the way the scores are distributed across the different categories. This will tell us which neighborhoods have the same characteristics, and which are different from each other. This avoids splitting hairs, because it uses all of the data simultaneously, rather than summarizing the data down to a single number for each neighborhood.

The analysis

A phylogenetic network is ideal for doing this sort of thing, as I have emphasized many times in this blog, and so I have constructed one. As my analysis of choice, I have used the manhattan distance (appropriately enough!) combined with a NeighborNet network. Neighborhoods that are closely connected in the network are similar to each other based on the various characteristics, and those that are further apart are progressively more different from each other.

Click to enlarge.

I have color-coded the neighborhoods based on their borough, using roughly the same colors as in the map shown above.

I have also placed an asterisk next to the top five neighborhoods based on their total scores. Two of these neighborhoods are near each other in the graph, with two a bit further away, and one is quite distant from the others. This indicates that, even though they have very similar total scores, these neighborhoods are actually quite different.

In general, the network shows a trend from Manhattan (at the right-hand end of the graph) to Queens and the Bronx (at the left-hand end), via Brooklyn (stretching through the middle). This seems to neatly summarize the overall impression of the relationships among the areas of New York, at least as it is usually presented to outsiders. So, I think that the network analysis has been a successful one, in the sense that it provides a useful picture of the relationships between the neighborhoods.

Going deeper, many of the detailed patterns in the network graph are fairly obvious. For example, (at the right-hand end of the graph) the association of the southern Manhattan neighborhoods of Soho, Central Greenwich Village, Tribeca, Battery Park City, and the Financial District should surprise no-one. Similarly, (at the top of the graph) the linking of Manhattan's Inwood with the nearby Bronx neighborhoods of Belmont, Bedford Park and Riverdale is not unexpected. Furthermore, (at the left-hand end of the graph) the connection of Astoria, Woodside, Jackson Heights, and Flushing (in north-western Queens) with Cobble Hill, Boerum Hill, and Bay Ridge (in western Brooklyn) is hardly surprising, even though the two borough areas are geographically separated.

Other patterns are less obvious, and thus more intriguing, such as the apparent similarity of Chinatown (southern Manhattan), Central Harlem (northern Manhattan), Co-op City (the Bronx), and West Brighton and New Dorp (both Staten Island) (at the bottom-left of the graph). This bears looking into, should you be looking for somewhere to live in New York. Perhaps the oddest juxtaposition is that of Chelsea (midtown Manhattan) with Corona Park (Queens) and Washington Heights (northern Manhattan).

Another possible use of the graph is that it makes suggestions for areas that might be suitable as alternatives to any neighborhood that is out of reach on the Affordability / Housing Cost criterion. That is, we might consider areas that are similar based on the other criteria and yet differ in Affordability. For example, Park Slope (northern Brooklyn) differs dramatically in Affordability from the Nolita & Little Italy neighborhood (lower Manhattan), and yet the only other characteristic they differ greatly on is Shopping & Services. Williamsburg, Greenpoint, and Carroll Gardens & Gowanus are indicated in the network as other neighborhoods worth considering.

It seems unlikely, however, that anyone looking for a substitute for the Upper East Side of Manhattan (one of the most expensive neighborhoods in the USA) is going to look at Sheepshead Bay, as suggested by the network — the two neighborhoods differ dramatically in Transit Proximity, since Sheepshead Bay is way down on the Atlantic coastline. Nor are those looking for a replacement for the Upper West Side going to consider Brooklyn's Prospect Heights — these two differ more than somewhat in Housing Quality, for example. So, good though it is, the suggestions made by the network graph are not perfect!

Postscript

There is one other ranking scheme that I know of, at the StreetAdvisor Best Neighborhoods web page [on that page, click on Neighborhoods]. It is described as follows:
Our rankings begin with reviews written by locals. Each review contains certain scoring elements that tell us how good, or how bad a place is. We then combine all the scores and apply a 'fairness' factor that takes into account things such as volume of reviews, age of reviews and the type of person writing a review. We then apply a rank so we can compare and sort locations.
You will find many of the rankings odd, to say the least. For example, it seems doubtful that Country Club (the Bronx) is the "3rd best neighborhood in New York City" (after Carnegie Hill and Gramercy Park).

Not the least of the oddities is that the Upper East Side (7.6) scores much less than neighboring Carnegie Hill (9.4) and Lenox Hill (8.1). Indeed, it scores worse than parts of Brooklyn (Carroll Gardens, Clinton Hill, Brooklyn Heights, Park Slope, Bay Ridge), Queens (Glendale, Richmond Hill, Forest Park), the Bronx (Country Club, Schuylerville) and Staten Island (Huguenot).

You can access the individual neighborhoods within the boroughs at these web pages:
Manhattan
Brooklyn
Queens
Bronx