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RE: AI-GEOSTATS: Exploring bivariate/multivariate relationships a s a function of distance

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  • Munroe, Darla K
    Thanks for your message, Gaston. I m sorry if I was unclear. Yes - I am definitely going to run a spatial autoregressive model. I am quite familiar with those
    Message 1 of 1 , Mar 23, 2004
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      Thanks for your message, Gaston.

      I'm sorry if I was unclear.

      Yes - I am definitely going to run a spatial autoregressive model. I am
      quite familiar with those approaches.

      What I want is to best *explore* how price changes with distance to the
      greenway, and particularly find out over *exactly* what range the
      relationship is negative.

      Basically, there is a change in slope in the scatter plot - over short
      distances, the slope of price over distance to greenway is negative, but
      then it goes to 0 or is even positive. My interpretation is this is that
      the amenity benefit of the greenway is subject to a pretty extreme distance
      decay. I want to know more or less exactly what that critical distance is.

      The other, maybe less problematic, problem is simply that the decay is not
      completely monotonic.


      -----Original Message-----
      From: Gastón Pezzuchi [mailto:gpezzuchi@...]
      Sent: Tuesday, March 23, 2004 3:05 PM
      To: Munroe, Darla K
      Subject: Re: AI-GEOSTATS: Exploring bivariate/multivariate relationships as
      a function of distance


      Darla:

      I am nor particularly well versed in spatial multivariate methods, but I
      have found that the best ones are:

      a) Geographically Weighted Regression,
      b) Spatial Autoregressive Model
      c) Spatial Error Model

      I do not know which method are you using, or how are you modeling the
      space in your problem, and perhaps what I am telling you is something you've
      already taken into consideration, but classical multivariate methods aren't
      good with spatial data both due to heterogeneity and dependence.

      Personally I would consider using GWR methods...

      Hope it helps,

      Yours,

      Gastón Pezzuchi

      ----- Original Message -----
      From: "Munroe, Darla K" <dkmunroe@...>
      To: <ai-geostats@...>
      Sent: Tuesday, March 23, 2004 1:17 PM
      Subject: AI-GEOSTATS: Exploring bivariate/multivariate relationships as a
      function of distance


      > Hello group,
      >
      > I apologize in advance for my lack of geostatistical knowledge. I
      > only dabble in these approaches.
      >
      > I'm working on a project whose aim is to estimate a real estate
      > premium based on proximity to a greenway. The client is a non-profit
      > agency who wants to promote "environmental sustainability", and of
      > course wants to
      tell
      > the county that there is a huge positive amenity benefit from being
      > closer to the greenway. There is also an incredibly quick distance
      > decay; the benefit to the greenway quickly erodes over distance, maybe
      > even just a
      few
      > hundred meters.
      >
      > Problem is, the relationship is so darn complex. First of all, the
      > relationship is not monotonic. Presumably, people want to locate
      > within walking distance of a greenway, but not necessarily right on
      > top of the greenway. Also, there are nice greenways, and bad
      > greenways. The
      greenway
      > follows the river, so it runs through some not-nice neighborhoods, and
      > in those cases, the greenway is a potential conduit for crime. I have
      > looked at distance to parks in this area, and the effect is similar -
      > there are some nice parks, and some "drug" parks, so the amenity
      > benefit varies.
      >
      > Of course, I can control for a lot of these factors in multivariate
      > regression, but the problem is, I need to be able to best examine the
      > relationship between distance to the greenway and residential sales
      > prices to figure out exactly what the distance decay might be, and
      > over what
      range,
      > to best set up this variable in MVR, and to select sample parcels for
      > regression. I've done simple scatter plots of price over distance to
      > greenway, and it's pretty noisy. The relationship is negative for a
      > short distance (i.e., the closer to the greenway, the higher the
      > value), and
      then
      > basically goes to 0 or slightly positive.
      >
      > Can anyone suggest some methods for best identifying the RANGE of
      > distance over which this relationship is negative?
      >
      > Thanks,
      > Darla Munroe
      >
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