Research Methods

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Research Methods
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9th grade 16,322 Some high school
19,095 High school grad 25,081 Some
college(no degree) 29,903 Associate's degree
31,358 Bachelor's degree 41,361 Master's
degree 50,704 Professional degree
76,659 PhD 71,541
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Nation X TV's per capita Y life exp.
(years) Angola 1/200 44 Australia 1/2
76.5 Cambodia 1/177 49.5 Canada 1/1.7
76.5 China 1/15 70 Haiti 1/234
53.5 Japan 1/1.8 79 Russia 1/3.2 69 UK
1/3 76 USA 1/1.3 75.5 Yemen 1/38 50
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X driving credit score Y average
incurred loss per policy (1-worst 10, 2-next
lowest 10, , 10-best 10) 1 918 2 846 3
791 4 707 5 703 6 681 7 631 8
584 9 568 10 558
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State X avg. spending per student (in ) Y
mean SAT Math score AL 5,885 554 AR 5,278
550 FL 6,170 499 GA 6,929 489 LA 6,037
562 MS 5,175 551 NC 6,346 499 SC 6,631
488 TN 5,687 553
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Team X payroll (millions of ) Y wins in 2005
regular season NYY 208.3 95 BOS 123.5 95 NYM
101.3 83 LAA 97.7 95 PHI 95.5 88 STL 92.1
100 SF 90.1 75 SEA 87.7 69 CHC 87.0 79 ATL
86.5 90 LAD 83.0 71 HOU 76.8 89 CHW 75.2
99 BAL 73.9 74 DET 69.1 71 SD 63.3 82 AZ
62.3 77 CIN 61.9 73 FL 60.4 83 MIN 56.2
83 TEX 55.8 79 OAK 55.4 88 WAS 48.6 81 COL
48.2 67 TOR 45.7 80 CLE 41.5 93 MIL 39.9
81 PIT 38.1 67 KC 36.9 56 TB 29.7 67
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Cleveland best value for the money
How much per win?
Yankess 2.18 million Tampa Bay
440,000 Phila 1.08 million
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• Gathering Data
• Experiments
• Observations
• Case Studies
• Surveys
• Longitudinal Studies
• Cross-cultural studies

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• Samples
• Small group of the tested population
• Must be representative of the larger population
• To avoid bias
• Random Sample individuals picked purely by
  chance (every individual has an equal chance of
  being selected)
• Stratified Sample individuals deliberately
  chosen from various sub-groups of the population.
• Ethnicity, age, sex, political/religious
  affiliation, etc

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Size of sample is important for accuracy More
data better results!
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• Correlation describes the degree of relatedness
  between two variables
• Positive correlation both variables move in the
  same direction (both up OR both down)
• Ex. IQ and test scores
• Attendance and grades
• School cell phone use and detentions

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Negative correlation variables move in opposite
directions. Ex. Brushing teeth and number of
cavities. Life expectancy and smoking.
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Children raised in homes with more appliances
tend to perform better in school. Therefore,
appliances improve intelligence.
Correlation does not imply causation
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but it can be used to make predictions.

Lifetime earning potential
education
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Height (inches)
Head Size (inches)
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• Experiments
• Control the situation, environment
• Decrease the influence of outside factors
• Hypothesis educated guessestablish the
  foundation of the experiment
• Independent variable the factor the experimenter
  changes to see its effect
• Dependent variable the factor that is measured
  to see how it was affected by the independent
  variable

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Controlled experiment Hypothesis Red light
helps plants grow better than blue light
Independent variable Color of light
24 hrs/day
12 hrs/day
Dependent variable Height of plant
1 liter of water/day 15 degrees Celcius
.5 liters of water/day 20 degrees Celcius
Every factor other than the independent variable
should remain CONSTANT!
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Experimental group gets the independent
variable Control group gets treated exactly the
same as the experimental group EXCEPT for the
independent variable
Experimental results must be replicable. Results
published in a journal then reviewed and
critiqued by peers. If results can be replicated
and the methods and conclusions accepted by the
scientific community the results are accepted as
either supporting or not supporting the
hypothesis. You cannot really PROVE things in
science!
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One trap to avoid in research Self-fulfilling
prophecy The researcher finds what they expect
to find and ignore or overlook other important
facts, data, etc. The researcher may do this
unknowingly, which is why we publish
results Does a researchers beliefs, attitudes,
or feelings affect the way he or she will
interpret the results of an experiment? If I
work for an oil company or a utility company that
uses coal, will I be as likely to believe in
global warming, or will I only look at data that
support what I already believe? (cherry picking
the data)
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Solution The Double-Blind Study
vs
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Single-blind study the test subjects are
blind, but the researcher knows the Coke and
Pepsi cups and could influence the results with
body language, voice inflection, eye movements,
etc. (intentional or not) Double-blind study
both the test subjects and the researcher are
blind. If neither know the products in the
cups, no improper influence could affect the
results.
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• 2. Naturalistic Observation
• To understand how the subjects behave naturally
• Avoid disturbing or interacting with the subjects

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• 3. Case Studies
• Intensive investigation of an individual or group
• Usually focus on a particular problem or
  experience
• Combine long-term observations (psychological
  tests, behavior reports, self-reports, etc)
• Lacks a control group for comparison

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• 4. Surveys
• Most practical way to gather data on attitudes,
  beliefs, and experiences from a large group of
  individuals quickly and easily.
• Interviews allow modification of the question
  if needed
• Questionnaires
• Less time
• Results more uniform
• Eliminates influence of researcher

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• 5. Longitudinal Studies
• Covers long periods of time
• Study and restudy the same group at regular
  intervals to determine changes in behavior
• Time consuminggood results may take years to
  obtain and publish

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• 6. Cross cultural studies
• Comparisons of the way people in different
  cultures behave, think, feel, etc
• Certain values appear to be universal, but
  cultural differences do affect the development of
  moral reasoning.