This document provides an overview of text analytics tools and techniques. It discusses the five pillars of text analytics: search, filter, code, cluster, and classify. It also describes the open-source tool DiscoverText and how it can be used to perform tasks like searching Twitter data, having humans code tweets, creating topic models via clustering, and training machine learning classifiers to classify texts. The document emphasizes that validation of models and iterative refinement is important when performing computational analysis of text data.

1. Tools for Text
Dr. Stuart Shulman
@stuartwshulman
stu@texifter.com
Prepared for the Digital Methods Initiative Winter School 2014
University of Amsterdam
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2. Acknowledgements
Richard Rogers
The National Science Foundation
Mark J. Hoy
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3. Plan of Attack
A few high level thoughts
Five pillars of text analytics
Getting started on DiscoverText
A small collaborative project
The twittersifter.com beta release
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4. “A funny thing happened…”
A brief history of DiscoverText
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5. A Master Metaphor: Sifter
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6. An Open Source Kernel
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7. Three Primary Tasks in CAT
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8. Classification of Text
A 2500 year-old problem
Plato argued it would be frustrating
It still is…
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9. Grimmer & Stewart “Text as Data”
Political Analysis (2013)
Volume is a problem for scholars
Coders are expensive
Groups struggle to accurately label text at scale
Validation of both humans and machines is “essential”
Some models are easier to validate than others
All models are wrong
Automated models enhance/amplify, but don’t replace humans
There is no one right way to do this
“Validate, validate, validate”
“What should be avoided then, is the blind use
of any method without a validation step.”
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10. (Patent Pending)
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11. Three Important Books
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12. One Particularly Important Idea
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13. Five Pillars of Text Analytics
Search
Filter
Code
Cluster
Classify
You can execute all five using DT
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14. Pillar #1: Search
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15. Search for Negative Cases
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16. Defined Search (Multi-term)
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17. Pillar #2: Filters
Remember
this filter
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18. Another Common Filter
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19. !19

20. Pillar#3: Human Coding
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21. Keystroke Coding is Fast
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22. Coding Off a List is Faster
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23. Data Cleaning is Fundamental
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24. Pillar #4: Clustering
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25. !25

26. Latent Dirichlet Allocation
(LDA) Topic Models
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27. LDA on the Christie Data
Data is still processing…
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28. Pillar#5: Machine-Learning
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29. Getting Started on DiscoverText
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30. Use the Key in Your Email
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31. Note the Peer Visibility Setting
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32. Peers Make Collaboration Possible
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35. !35

36. Perhaps a Trending Topic
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37. !37

38. The Basics
Raw Data
Subsets of Data
Data Humans or
Machines Classify
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40. Grab Some Twitter Data
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41. Create an Empty Archive
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42. Login to a Twitter Account
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43. Enable via OAuth
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44. Ready to Query Twitter
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45. Use Operators to Refine Queries
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46. Set the Frequency of Fetches
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47. Data Will Start Flowing
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48. Data List View
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49. Best List Settings for Twitter Data
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50. Use Buckets to Refine Lists
Search results go into buckets
“Defined search” is a multi-term filter
Meta data filters also useful for buckets
Buckets focus the text analytic process
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52. Create a Dataset to Code
Any archive or bucket
Use the random sampling tool
Standard: All coders get all items
Triage: Coders get next uncoded item
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54. Select from Three Coding Styles
Default: Mutually Exclusive Codes
Option 1: Non-Mutually Exclusive Codes
Option 2: User-Defined Codes
(Grounded Theory)
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56. Assign Peers to Code a Dataset
How many coders?
How many items need to be coded?
How many test or training sets?
There are no cookbook answers
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57. Look at Inter-Rater Reliability
Highly reliable coding (easy tasks)
Unreliable coding (interesting tasks)
If humans can’t, neither can machines
Some tasks better suited for machines
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58. Adjudication: The Secret Sauce
Expert review or consensus process
Invalidate false positives
Identify strong and weak coders
Exclude false positives from training sets
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61. Use Classification Scores as Filters
Iteration plays a critical role
Train, classify, filter
Repeat until the model is trusted
Each round weeds out false positives
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62. Classifier Histograms: More Filtering
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63. Track Your Progress
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66. !66

67. Running the Classifier
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68. !68

69. Filter by Classification
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70. Filtered List >95% Not Chris Christie
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71. http://beta.twittersifter.com

74. Thanks for Having Me!
Dr. Stuart Shulman
@stuartwshulman
stu@texifter.com
discovertext.com
twittersifter.com
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