Ch 2: Data

Question 1

spatial

Answer 1

where an object is located or an event has occurred

Question 2

temporal

Answer 2

when the location and attributes were accurate (when collected)

Question 3

attribute

Answer 3

what characteristics the object or event has

Question 4

example of spatial charactertistic

Answer 4

Spatial characteristics of data, like location of state boundaries(or address, coordinates) are needed to put the data on a map

Question 5

example of temporal characteristic

Answer 5

Temporal characteristics refer to how data represent a “snapshot” of what things were like at the time the data were collected, such as census data from 2000

Question 6

example of attribute characteristic

Answer 6

Attribute characteristics describe the nature of a location (population, income, etc)

Question 7

2 main methods of spatial data collection

Answer 7

ground surveying and remote sensing

Question 8

ground surveying

Answer 8

involves a person or mechanism that observes or interacts with people or the environ. in a particular place

Question 9

remote sensing

Answer 9

refers to collecting data from afar, often by taking pics from a plane or satellite

Question 10

ground surveying in depth

Answer 10

Ground surveying conducted through individual/mechanism interacting with a particular place
Can include a person collecting locational data with handset that works with GPS, constellation of satellites that beam signals to earth where they can be used to determine position
Surveys involve talking to people or traveling to different locations to gather info
Another kind of ground surveying occurs at weather stations that measure temp and other climatological info at a given location

Question 11

what process is ground surveying similar to?

Answer 11

geo coding

Question 12

what is geocoding

Answer 12

data with locational elements (address, zipcode) are matched to known ground coordinates

Question 13

land surveying

Answer 13

-determines location
Use tools to determine precise positions of locations by triangulating from the position of known locations
Land surveyors helped map out many countries, working outward from known to unknown locations

Question 14

gps in depth

Answer 14

GPS are constellations of satellites that orbit Earth
Satellites transmit signals to earth’s surface to indicate their position in space and a precise time signal
Device equipped with GPS receiver can interpret these signals and find device’s location earth

Question 15

what type of surveying is gps considered

Answer 15

Considered ground surveying since it’s the handset or GPS unit that’s determining position from satellite signals

Question 16

drawbacks of gps

Answer 16

signals can be blocked by solid objects and getting a strong signal can be hard, limited number of satellites orbiting Earth, depending on quality of handset GPS coordinates could be inaccurate
Space segment system based on velocity

Question 17

control segment

Answer 17

ground stations that monitor and maintain the satellite vehicles

Question 18

user segment

Answer 18

receivers detecting and interpreting signals (use signals to calculate position)

Question 19

geo coding

Answer 19

process of attaching a geographic location to address information

Most use some form of database of addresses whose locations are precisely known

Question 20

surveys

Answer 20

gather attribute info about individuals, households, businesses or area
Data gathered can be linked to location on a map
Census collects data on all members of a population

Question 21

sensors

Answer 21

used to measure a wide array of human and environmental facts
Location determined by GPS, ground surveying or geocoding

Question 22

remote sensing

Answer 22

-collected at a distance from object they are studying
Some sensors collect imagery with cameras
Detect different non visible parts of the electromagnetic spectrum, infrared (heat)
Used for monitoring changes in the environment over large areas (deforestation)

Question 23

metadata

Answer 23

data about data that lets you assess how well the data can work with other data

Question 24

example of metadata

Answer 24

Such as the content, source, lineage, methods, developer, coordinate systems, extent, structure, spatial accuracy and the responsible organization for spatial data

Question 25

census data

Answer 25

Primary source of social data used by government, nonprofits and businesses

Question 26

background to census

Answer 26

US census conducted every 10 years and collects info about the race, age and housing situation of the population
Purpose is to determine the number of seats each state will have in the US House of Representatives, legislative branch of government
Censuses also determine how billions of dollars in federal funding is distributed for many purposes (education, health care, environmental protection, transportation, etc)
Data from census and ACS (American Community Survey) are collected from each household, but in order to preserve privacy and to make data easier to use, Census Bureau combines the data to larger geographic areas
Canadian census → critical for allocation of government resources and conducted every 10 years
Census data used to redraw ridings used to elect people and process based on: pop. equity, community identity, historical patterns and maintaining a manageable geographic site

Question 27

limitations of census data

Answer 27

Primary challenge is accuracy and undercounting (homeless are missed in the count)
Plenty of topics aren’t covered, quantity and wording of questions asked changed over time, data not always available for all places or geographic areas

Question 28

key concepts to consider when choosing data to analyze a specific problem

Answer 28

Resolution, accuracy and interoperability with respect to 3 elements of spatial data (location, attributes, time)

Question 29

resolution

Answer 29

Describes the breadth or specificity of data you are examining
3 main types: spatial, attribute and temporal
Higher resolution corresponds with smaller areas over which data are collected, narrower distinctions between categories, or shorter times between data collection

Question 30

spatial resolution

Answer 30

measure of the smallest object that can be resolved by sensor

Question 31

attribution resolution

Answer 31

deals with the degree to which distinctions are made between categories
-Data split into many categories provide more detailed distinctions and higher attribute resolution

Question 32

temporal resolution

Answer 32

frequency with which data is collected

Question 33

accuracy

Answer 33

Describes how well data on a map aligns with objects in the world

Question 34

spatial accuracy

Answer 34

how well an object’s location on the map matches its location in the world

Question 35

example of spatial accuracy

Answer 35

boundaries between countries drawn incorrectly, GPS points offset if signal blocked, etc

Question 36

attribute accuracy

Answer 36

-whether characteristics reported about an object are true about that object in the world

-Inaccuracies show up in survey data if participants don’t respond, misunderstand or provide false information; or when estimating values for small area based on small number of responses

Question 37

temporal accuracy

Answer 37

concerned with whether details about an object are up-to-date with respect to changes in the world
Accurate at time of collection but because of changes to social and physical landscape → becomes inaccurate (e.g. printed reference map)

Question 38

interoperability

Answer 38

Describes how well two different datasets work with each other

Question 39

spatial interoperability

Answer 39

how well do spatial units match up

E.g. zip codes and census tracts are spatial units for which data are frequently collected but their boundaries are rarely the same
Zip Code level data and census tract level data have poor interoperability as they don’t show characteristics for same group of people

Question 40

attribute interoperability

Answer 40

how well do the categories of 2 datasets match?

E.g. in 2010 census, people could pick from between 15 racial categories with option of selecting multiple categories
By comparison, in the 1850 census, individuals were divided into only three racial categories: “white,” “black,” or “mulatto.”
These two datasets have poor attribute interoperability because they have very different attribute resolution and do not have matching categories.

Question 41

temporal interoperability

Answer 41

how well do reported times match up?

Of most concern if making an argument about what things are like at one point in time but your data are not from same point in time
E.g. if you are working at a nonprofit that’s trying to compare number of children ages 0-5 to the number and location of early childhood centers in an area, most accurate count of children is from the 2010 census, but your organization has information about childhood centers collected in 2015
These two datasets have poor temporal interoperability because no children who were 0-5 at the time of the census would still be in that age bracket in 2015.
It would be hard to determine whether childhood centers are appropriately located based on this data.

Question 42

trilateration

Answer 42

Need 3 reference points and exact location is where all 3 intersect
Gives coordinates (3 points)
In space, reference points are satellites

Question 43

metadata

Answer 43

data about data that describes factors such as the content, source, lineage, methods, developer, coordinate systems, extent, structure, spatial accuracy and the responsible organization for spatial data

Question 44

geocoding

Answer 44

process of attaching a geographic location to some sort of address information
-it takes an address and transforms it into a pair of coordinates that can be plotted on a map