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

: : : :

: : : :

: : : :

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