| 11.188: Urban Planning and Social Science Laboratory |
Consider the grid cell in the north-west corner of Cambridge that contains the most expensive sale (i.e., highest value of REALPRICE) in the sales89 data.
(1) What is the reported / actual "realprice" value for this grid cell? ___________________
(2) What is the interpolated value for this grid cell using the sales89 data with a power coefficient of 2 (i.e., the sales89_pw2_2 file)? ___________________
(3) Draw a scatterplot (in Excel) with the x-axis showing six values of the coefficient (0, 1, 2, 3, 4, and 5) and the y-axis showing the corresponding estimation errors (estimation error = interpolated estimate - actual "realprice" value) for this grid cell using the sales89 data. Comment on the trend you observe in the scatterplot. What challenges might we face if we chose an overly small or overly large power coefficient? Provide separate explanations for the two cases.
(4) What is the interpolated value for this grid cell using the block group median housing value data at the centroid level (i.e., the hvalue_point_2 file)? ___________________
(5) What is the interpolated value for this grid cell using the block group median housing value data at the polygon level before smoothing (i.e., the cambbgrpgd_2 file)? ___________________
(6) What is the interpolated value for this grid cell using the block group median housing value data at the polygon level after smoothing (i.e., the cambbgrpgd_3 file)? ___________________
(7) Comment on the differences you observe among Questions 4, 5, and 6. How does the choice of point (centroid) vs. polygon matter? Are the hot-spots more concentrated or diffuse? Does one or another approach lead to a broader range of spatial variability? To what extent does smoothing change the interpolated estimate? Does smoothing reduce the estimation error?
(8) What is the interpolated value for this grid cell using a simple average of the sales89 data and the block group median housing value data at the polygon level after smoothing (i.e., the raster_calc file)? ___________________
(9) Include a map of the raster_calc file with appropriate supporting elements and design.Last modified: March 31, 2021 by Rounaq Basu
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