Video #20 (Uncertainty)

Question 1

Why are errors important?

Answer 1

They can invalidate our analysis

Question 2

Where is the largest source of errors typically?

Answer 2

In the data aqusision faze

Question 3

What is accuracy?

Answer 3

How accepted the values of data are represented

Question 4

One of the downsides of highly accurate data is…

Answer 4

It is expensive to produce or record

Question 5

Because of the inevitable errors and inaccuracies, we standardize accuracy using…

Answer 5

A margin of error

Question 6

Precision is…

Answer 6

How specific and how deep the data is (0.200 is more precise than 0.2)

Question 7

Precision in GIS usually entails…

Answer 7

Greater detail of a map

Question 8

True of false: Extremely precise data is more accurate data

Answer 8

False; Precision =/= Accuracy

Question 9

What is the level of precision?

Answer 9

The accepted precision value which is dependant on what you are surveying (width of road can be less precise than width of Canada)

Question 10

What is data qualtiy?

Answer 10

The accuracy and precision of the data collected.

Question 11

Data quality is assessed in…

Answer 11

Data quality reports

Question 12

What are the types of errors?

Answer 12

PAC

1) Positional error
2) Attribute error
3) Conceptual error

Question 13

Positional error is…

Answer 13

The error of position in a GIS, possibly by using the wrong scale or coordinate system

Question 14

Attribute error is…

Answer 14

The non-spatial analysis of data may be inaccurate (single family home may actually be a condo) or imprecise (home instead of condo or lacking what floor a person may live on in a condo)

Question 15

Conceptually error is…

Answer 15

The use of inappropriate categories or data used (having elevation as a dataset while analyzing income in proximity to city centres)

Question 16

What is the issue with the “How Many Lakes in Finland?” study?

Answer 16

The data was extremely precise which raised questions about if it was valid or accurate, and the definition of a lake wasn’t given (is a pond a lake?)

Question 17

Misclassification is…

Answer 17

Using information to represent a phenomena in an ineffective way. The % of voters would be an ineffective way of classifying or categorizing GDP

Question 18

How is the threshold of data quality determined?

Answer 18

By the user’s instinct. It should be appropriate for the project

Question 19

The GIS software can provide some sources of error itself. An example of this is…

Answer 19

Fuzzy borders or impreciseness (think walking distance on my final project)

Question 20

What is the recognition of error?

Answer 20

The levels of error that are present in the GIS, which should be acknowledged by the author

Question 21

What are the 3 major sources of error?

Answer 21

1) Obvious errors
2) Natural variation errors
3) Processing errors

Question 22

Why are obvious and natural variation errors more easily detectable than processing errors?

Answer 22

Processing errors are subtle and hard to identify, beginner users may be unfamiliar with errors that can occur in processing

Question 23

What are some examples of obvious errors?

Answer 23

Age of data, map scale, relevance of data, accessibility etc.

Question 24

What are the 2 issues with the obvious-age of data error?

Answer 24

The space it is trying to represent has changed. A map of Vancouver in the 1930s will be inaccurate today. Standards have also changed since the map was produced

Question 25

What is the obvious-areal cover error?

Answer 25

Some data may be left out of skewed

Question 26

What is a obvious-map scale error?

Answer 26

The scale used varies how fine your data may be. A scale of 10:1 will be more accurate than 400,000:1 in showing a house layout

Question 27

What is a obvious-sample size error?

Answer 27

A greater sample gives more precise results so a small sample isn’t as appreciated

Question 28

What are some processing errors?

Answer 28

Numerical errors, topological analysis, classification and generalization, digitizing

Question 29

What are processing-numerical errors?

Answer 29

Errors that may occur because some hardware or software may not be well equipped to deal with what the user is inputting or rounding in processes

Question 30

What are processing-topological errors?

Answer 30

Errors where the process doesn’t recognize certain topography or recognize what the user is inputting

Question 31

What are processing-classification errors?

Answer 31

Errors where the classification of data is unclear

Question 32

What are processing-digitizing errors?

Answer 32

Errors where the software recognizes coffee spills on physical maps as polygons

Question 33

What is data consistency and why is it important?

Answer 33

Data consistency is the consistency of measurements and scale in data, and it’s important because it sets a standard of measurement and data can blend well together

Question 34

What is the problem with missing data?

Answer 34

Missing data can change the narrative of the data by misrepresenting a phenomena

Question 35

What could a reason some road data is missing?

Answer 35

The definition of a road could change between sources

Question 36

What is meta-data?

Answer 36

Data about data. Data includes lineage which is the meta-data

Question 37

What are the six important things included in meta-data?

Answer 37

1) Specification of sampling methodologies
2) Definition of terms
3) Measurement specification
4) Documentation of classification system
5) Data model methodology and history
6) Purpose of study

Question 38

What should you do in reaction of error and uncertainty?

Answer 38

Learn why it is inaccurate, express it and engage with it