Lecture 5: GIS Vector Analysis

What to do with points, lines, and polygons

What are the big five data quality aspects?

• Positional Accuracy

• Attribute Accuracy

• Completeness

• Logical Consistency

• Lineage

Positional Accuracy (quantitative accuracy)

Spatial, measures how close the reported or mapped location of an object is to its true ground position

Attribute Accuracy

a feature is what the GIS/map purports it to be (a railroad is a railroad, and not a road)

Completeness

the reliability concept from experimental design/stat. inf.

how much data is missing?

Logical Consistency

the degree to which a dataset adheres to the pre-established rules, structure, attribution, and topological relationships of its data model

Lineage

Identifies the sources from which the data were derived

should be included in METADATA

What is metadata? How is it different from standards?

Metadata is data about data (description)

Standards are the rules or guidelines for how data should be created, formatted, stored, or shared (rules)

How did GIS get started?

Canada Land Inventory (Roger Tomlinsom), US Census, Harvard Lab

When did googlemaps launch?

2005

what type of data are shapefiles?

vector

What type of data is grid files?

raster

What are the vector data types?

• Point, line, polygon simplifies matters

• Each record (row in attribute table) is a spatial object (may be a single polygon or multiple things, example would be multiple polygons that are one state or one country - one observation)

why are Aggregation units special

They balance individual privacy protection with precise geographic and statistical ultitly.

What is a choropleth map?

A thematic map where predefined geographic areas (countries, states, counties) are shaded or ptterned in proportion to the value of the statistical variable being displayed

What are the types of vector analysis

1. Distance / Area or… Query / Selection

2. Buffering Overlay

3. Geocoding Network Analysis

Distance / Area, Query / Selection

examining parameters of the spatial objects (points, lines, areas) and defining questions about attributes and spatial relationships that describe those objects.

Buffering Overlay

These types of operations focus on spatial relationships and the altering of geometry to describe relationships beyond those found in the initial objects.

Geocoding

Creating absolute location (lat, long) from relative location (usually an address)

Aggregation vs. Privacy

Data aggregation reduces individual privacy risks by combining multiple data points into a summary statistic, but it does not provide a complete privacy guarantee on its own

Three types of vector data

Point, line polygons

What are the different types of positional accuracy

Positional,
Horizontal, Vertical, Temporal (Time)

What map would be used to display how a theme is distributed across
space (Reference or Thematic)

Thematic