Chapter 5: Observation and Description: Problems

1
Chapter 5 Observation and Description Problems

• Selecting an unbiased Sample
• Random Sampling
• Sampling Bias Concerns
• Observer Effects
• Observation Bias
• Inferential Bias

2
Sampling

• Sample and Population
• Problem of Sampling Bias--Biased sample
  surveys--Self-selected samples--Literary Digest
  example

3
Obtaining Representative Samples

• Random Sampling--Every individual has an equal
  chance of being selected
• Variants of Random Sampling--Multistage
  sampling--Systematic Sampling

4
Random Sampling

• Bin of name tags
• Random Number Table (Mook)
• Computer-generated Random Numbers
• Web Page/Software
• The problem of very large populations
• Phonebook
• No such thing as the population

5
Variants of Random Sampling

• Multistage Sampling
• Systematic Sampling-- Book-carrying example--
  Selecting a sample from our class

6
Other Approaches to Sampling

• Purposive Sampling
• Convenience Sampling
• Defined Population--Subjects Like These
• Generality Across Different Studies

7
Purposive Sampling

• Sometime select a group to study based on the
  question or concern of the research
• Specific Characteristics--e.g. Bennington College
  study

8
Convenience Sampling

• Default for behavioral research
• Availability and convenience
• Example mother-infant study
• Impractical to generate a truly random sample
  (e.g. of all two-year olds in U.S.)
• Serious Problem?

9
Why Convenience Samples Not a Serious Problem

• Limited Generality Unlikely
• Subjects Like These
• Reasonable Assumptions of Generality
• Cautions
• Generality from Diversity

10
When DO We Need Representative Samples ?

• When trying to understanding a Specific
  Population
• Example the voting population for an election

11
Observer Effects
12
Examples of Observer Effects

• Clever Hans
• Facilitated Communication
• Ekmans Research
• Animal Language--Koko
• Leading Questions--e.g. Loftus work

13
Controlling Observer Effects

• Concealment
• Adjustment to the Observer
• Deception
• Unobtrusive Measures
• Blind Observers

14
Getting Used to Observers
15
Observer Bias
16
Examples of Observer Bias

• Dont want to distort how we see or what we
  observe
• Judging tape of job applicant versus a
  patient
• N-Rays
• UFOS

17
Controlling Observer Bias

• Blind Observing
• Objective Measures
• Multiple Observers

18
Blind Observing

• Observers who dont know the theory or expected
  outcome
• Less the observer knows the better
• Automatic collection of observations--e.g. video
  taping
• Verbal Report Examples
• Job Applicants
• Bell Ainsworth study

19
Objective Measures

• Reduce Bias
• Harlow Rating degree attachment gt Time spent
  with each mother
• Mechanically/automatically recording time
• Look for some kind of Physical measurement

20
Multiple Observers

• Interobserver reliability at least
• Does not get rid of biases
• A check on the seriouness of the problem
• Training observers

21
Observer Bias in Everyday Life

• Backward played tapes with hidden messages
• How can you check this claim or other claims like
  it?
• Web Links
• http//www.reversespeech.com
• http//www.csicop.org/si/2000-03/reverse-speech.ht
  ml

22
Questions

• What is the mechanism or explanation for
  reversed speech?
• Is it plausible? How would you test the claim?
• Why would people believe this claim? What
  psychological mechanisms can explain it?
• What if two people heard the same messages?

23
Correlation and Causality

• Inferential Bias
• The Toaster Method of Birth Control
• Bell and Ainsworth--the Possibilities
• Current News Stories

24
ANY Correlation of X and Y

• X might cause Y
• Y might cause X
• Z might cause X and Y