adv gis quiz 2

Question 1

accessibility

Answer 1

relative ease by which the locations of activities such as work, school, shopping, recreation, and health care can be reached from a given location

Question 2

why measuring accessibility is important

Answer 2

• resources are scarce
• not uniformly distributed
• disadvantaged groups might suffer more from poor access

Question 3

how accessibility is determined

Answer 3

distributions of supply and demand and how they are connected in space

Question 4

four categories access can be classified into

Answer 4

potential vs revealed access
spatial vs aspatial access

Question 5

revealed accessibility

Answer 5

actual use of a service

Question 6

potential accessibility

Answer 6

probable utilization of a service

Question 7

spatial access

Answer 7

emphasizes importance of a spatial separation between supply and demand as a barrier or facilitator

Question 8

aspatial access

Answer 8

stresses nongeographic barriers or facilitators

Question 9

supply-demand ratio method

Answer 9

used before gis, computes ratio of supply vs demand to measure accessibility

Question 10

floating catchment area (FCA) method

Answer 10

catchment area floats from one residential location to another across the study area, and defines the accessibility for all locations

Question 11

problems with FCA

Answer 11

• assumes services within a catchment area are fully available to residents within that catchment area and residents use only those services
• doesn’t account for competition, which can decrease demand

Question 12

2SFCA - two step floating catchment area

Answer 12

repeats the process of floating catchment twice (for each supply location, search demand locations and for each demand location, search supply locations)
considers interactions between demands and suppliers

Question 13

how to measure catchment area for 2SFCA

Answer 13

use travel time NOT euclidean distance

Question 14

General Transit Feed Specification (GTFS)

Answer 14

incorporates data describing transit trips including route info, schedules, patterns, stops, services, trip paths, fares, and agency contact info

Question 15

what is trade area analysis necessary for

Answer 15

site selection of a retail store

Question 16

trade area

Answer 16

geographic area from which the store draws most of its customers and within which market penetration is highest

Question 17

spatial interaction

Answer 17

realized flow of passengers or freight between an origin and a destination
transport demand/supply relationship expressed over a geographical space

Question 18

complementarity (conditions for spatial flows)

Answer 18

there must be a supply and demand between the interacting locations

Question 19

intervening opportunity (conditions for spatial flows)

Answer 19

a location may offer a better alternative as a point of origin or as a point of destination

Question 20

transferability (conditions for spatial flows)

Answer 20

mobility must be supported by transport infrastructure, implying that the origin and the destination must be linked

Question 21

origin/destination matrices

Answer 21

require directional flow information between a series of locations

Question 22

gravity model

Answer 22

most common formulation of spatial interaction method
attraction between two objects is proportional to their mass and inversely proportional to their respective distance
ex. NYC and London have their own pops and they are ___ miles away, so multiply their pops and divide by miles to determine interaction strength

Question 23

analog method and regression models

Answer 23

uses existing store or several stores as analogs to forecast sales in a proposed similar facility
Y = b0 + b1x1 + b2x2 + ….
Y = store profits/sales
x = explanatory variables
b = regression coefficients to be estimated

Question 24

proximal area method

Answer 24

assumes consumers choose the nearest store among similar outlets

Question 25

proximal area method - consumer based

Answer 25

begins with consumer location and searches for nearest store consumers that share the same nearest store constitute the proximal area for that storeq

Question 26

proximal area method - stores based

Answer 26

constructs thiessen polygons from the store locations, and the polygon around each store defines the proximal area for that store layer of thiessen polygons may then be overlaid with that of consumers to identify demographic structures within each proximal area

Question 27

reilley's law of retail gravitation

Answer 27

consider both distance (or time) from and attractions (better prices or goods, etc) of stores

Question 28

reilly's law of retail gravitation equation

Answer 28

S1/d1x^2 = S2/d2x^2

Question 29

factors that influence trade areas

Answer 29

population of community proximity of other competing business districts mix of businesses in your community attractions traffic patterns

Question 30

convenience trade areas

Answer 30

based on the purchase of products and services needed on a regular basis

Question 31

destination trade area

Answer 31

based on the purchase of "major" products and services (like ikea)

Question 32

focus group use to define trade area

Answer 32

have participants shade on the map where they think the convenience and destination trade areas lie and use consensus

Question 33

simple rings - Defining Trade Areas Using GIS

Answer 33

choosing a certain distance radius

Question 34

data driven rings - Defining Trade Areas Using GIS

Answer 34

based on business district values such as volume of sales, store size, or number of stores rather than distance

Question 35

drive time polygons - Defining Trade Areas Using GIS

Answer 35

how long it takes to drive somewhere (ex downtown is a much smaller polygon than suburbs since you go much less distance over time in the downtown)

Question 36

thiessen polygons - Defining Trade Areas Using GIS

Answer 36

use thiessen polygons

Question 37

gravity modeling

Answer 37

probability of customer choosing a certain place relative to the other available places

Question 38

customer street address or zip code - Defining Trade Areas Using GIS

Answer 38

using street address or zip code to see what customers are coming from what areas

Question 39

regression analysis function

Answer 39

used to specify and test a functional relationship between variables

Question 40

why use regression?

Answer 40

explore correlations predict unknown values understand key factors

Question 41

regression equation

Answer 41

mathematical formula applied to the explanatory variables to best predict the dependent variable you are trying to model y = b0 + b1x1 + b2x2 + .... y=dependent variable x=independent variable b=regression coefficient

Question 42

regression coefficients

Answer 42

computed by the regression tool. they are values, one for each explanatory variable, that represent the strength and the type of relationship the explanatory variable has to the dependent variable

Question 43

p-value

Answer 43

small = small probabilities and suggest that the coefficient is actually important to your model

Question 44

r squared

Answer 44

quantify model performance (closer to 1 the better the line fits the data)

Question 45

residuals

Answer 45

difference between an observed outcome and its predicted value using the regression equation is the residual

Question 46

ordinary least squares (OLS)

Answer 46

most common regression technique regression line is chosen because it is the line that comes closes to most of the points

Question 47

six statistical checks

Answer 47

1. are the explanatory variables helping your model? (check asterisk) 2. are the relationships expected? (check sign) 3. are any of the explanatory variables redundant? (check VIF) 4. is the model biased? (p-value for the Jarque-Bera test) 5. are all key explanatory variables included in the model? (check residuals) 6. how well is the model explaining the dependent variable? (r squared and AIC)

Question 48

Global Moran's I statistic null hypothesis

Answer 48

attribute being analyzed is randomly distributed among the features in the study area

Question 49

geographically weighted regression (GWR)

Answer 49

provides a local model of the variable or process you are trying to understand/predict by fitting a regression equation to every feature in the dataset

Question 50

how GWR works

Answer 50

constructs separate equations by incorporating the dependent and explanatory variables of the features falling within the neighborhood of each target feature the shape and extent of each neighborhood analyzed is based on the neighborhood type and neighborhood selection method parameters

Question 51

number of neighbors

Answer 51

neighborhood size is a function of a specified number of neighbors, which allows neighborhoods to be smaller where features are dense and larger where features are sparse

Question 52

distance band

Answer 52

neighborhood size remains constant for each feature in the study area, resulting in more features per neighborhood where features are dense and fewer per neighborhood where they are sparse

Question 53

local weighting scheme

Answer 53

weights are determined using a kernel, which is a distance decay function that determines how quickly weights decrease as distances increase

Question 54

two kernel options in local weighting scheme parameter

Answer 54

gaussian weight bi-square weight