Numerical and Graphical Analysis
Finding and understanding patterns in data
The course so far
• Academic use of the web.• Publishing on the web• Analysing text• Manipulating textual lists• Tables• Numerical Analysis – why it matters• Graphical Analysis – a better way for
humanists
Lists
Ann Simms of Riverhead (Female) left £1560 died at age 89 years
Anne Potts of Ide Hill (Female) left £34 died at 17 years
Charles Forth of Chevening (Male) left £129 died at age 48 years
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: : : :
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George Salter of Riverhead (male) left £190, died at age 26 years
Data as a table
Forename Surname Village Gender Wealth Age at death
Ann Simms Riverhead Female £1560 89
Anne Potts Ide Hill Female £34 17
Charles Forth Chevening Male £129 48
Tables in a Spreadsheet
Spreadsheet Software
• Evolved from financial accounting practice.• Tabular data• Simple lists• Simple databases• Establish relationships within and between
data sets – simple statistics• Apply various functions• Plot Graphs and Charts
Applications in the humanities
• Maintaining and manipulating lists.
• Studying quantifiable information.
• Managing budgets and projects.
• Plotting graphs and charts.
• Compensating for weaknesses in other software applications.
• Building utility programs.
What would your tutor’s comments be?
“ During the early 19th century the population of London grew rapidly due to mass migration in from the countryside. The overcrowding caused by the rising population placed a strain on the sanitation systems causing a series of cholera epidemics, each worse than the one before.”
Quantify your statements: evidence?
“ During the early 19th century the population of London grew rapidly due to mass migration in from the countryside. The overcrowding caused by the rising population placed a strain on the sanitation systems causing a series of cholera epidemics, each worse than the one before.”
Poetry or Maths?
Reproduced from: Burrows J. (2002) ‘‘Delta’: a Measure of Stylistic Difference and a Guide to Likely Authorship’, Literary and Linguistic Computing, Vol. 17:3 p. 270.
Reproduced from: Burrows J. (2002) ‘‘Delta’: a Measure of Stylistic Difference and a Guide to Likely Authorship’, Literary and Linguistic Computing, Vol. 17:3 p. 280.
Examples
Social History
- New Poor Law
- Effects of the Industrial Revolution
- Voting patterns in elections
• Textual analysis - word frequencies etc George Orwell, Author attribution
Shakespeare or Marlowe
Why use numerical analysis?
• Wide variety of techniques –suitable for different types of data and questions.
• In the humanities it usually means ‘statistics’• Three Roles
- Summarise and compare data sets
- Test hypotheses
- Determine the significance of findings
Research Process
• What is your question?• What results would prove/disprove it?• Write a code book defining
- variable names- variable data type
- categories, ranges (‘controlled vocabulary’ for numeric data)
• Code data • Analysis• Interpretation
Authorship attribution
• Analysis of writing style
• Consistency of style
• Find frequently used words and look at their frequency in different portions of the book.
• End up with tables of frequencies and various indices – need to interpret them
Simple Statistics
• To summarise a set of data
- mean average value- mode most
common value - medianmiddle value - range
minimum, maximum and thedifference between them
Graphical Analysis
Allows us to:
• Summarise data
• Explore and identify areas for further study.
• To communicate the meaning of large volumes of data
Variance and correlation
• Are two things related?
- ability in one language to another- poverty and disease
- smoking and cancer
• Mostly easily done by drawing a graph.
Lung Cancer and Smoking
With regression line fitted
Variation in data
• How much variation is there in the data values?
• Standard deviation measures the deviation of the data from its mean
• Small value means very little spread
What does this mean?
Arrowhead length against width
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0 2 4 6 8 10 12
Length
Wid
th
What does this mean?Plot of Average Age and House Number
0
2
4
6
8
10
12
0 10 20 30 40 50 60 70 80
Average Age
Ho
us
e N
um
be
r
Warnings
• Think about what you are doing.
• A correlation does not mean there is a link.
• Even if there is a mathematical relationship it may not be a causal one.
• Beware of interpolated and extrapolated values.
Correlation? Tufte (2001) p. 15
René Magritte: La Trahison des Images (1928-9) (The Treachery of Images)
Los Angeles County Museum of Art