1. Preparing for Research
Info 271B Lecture 3
Coye Cheshire

2. Today’s Topics: Constructs, Variables and Causation Research Problems
Info 271B

3. Types of Variables Nominal Ordinal Metric Categorical
Dichotomous, Binary, Dummy Variables
Qualitative Variables
Ordinal
Rank Variables
Metric
Interval Variables
Ratio Variables
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4. Nominal Variables Binary/dichotomous Nominal/non-ordered polytomous
Example: Gender, event occurred or did not occur, etc.
When coded as 0/1, also called ‘dummy variables’
Nominal/non-ordered polytomous
Example: Employment Status
1= Employed
2= Unemployed
3= Retired
Three New Dummy Variables:
Employed (0,1)
Unemployed (0,1)
Retired (0,1)
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5. Ordinal Variables Ordered polytomous Example: Likert scales
Any ordered, categorical variable where the distance between categories may not be equal and meaningful
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6. Metric Variables Interval Ratio
Distance between attributes has meaning
Example: Celsius temperature, “likert-scale” questions
Ratio
Distance between attributes has meaning, and there can be a meaningful zero.
Example: Kelvin temperature, Count variables
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7. Constructs, Variables and Causation
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8. Time spent Difference in Weight Exercising between
Time 1 and Time 2
Difference in Weight
Scores between Time1
And Time 2
Gender
(Male =1,
Female =2)
Scale 1-5 of attitude
About Presidential
Candidate
Ethnic Identity
(10 Racial Types)
Owns and iPod or not
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9. An example theoretical model
Socioeconomic
Status
Academic
Achievement
Academic Ability
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10. Theoretical Model with Variables
Income
Job
Prestige
Socioeconomic
Status
Academic
Achievement
Academic Ability
Grades
Level of
Schooling attained
Math skills
Language
skills
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11. Causation and Causal Paths
Direct causal paths
Reciprocal causation
Indirect causation X Y X Y X Z Y
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12. Conditions of Causality
Covariation
Non-spurious relationship
Logical time ordering
Mechanism to explain how X causes Y X Y
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13. Hypothesis
“hypothesis statements contain two or more variables that are measurable or potentially measurable and that specify how the variables are related” (Kerlinger 1986)
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14. Propositions and Hypotheses
Propositions link concepts together with specific relationships
Hypotheses link variables together with specific relationships
Drug Use
Violence
Number of Times
Person Consumed
Drug X over Time T
Observed ‘violent acts’
Over time Y
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15. Next Class: Criteria for a Research Problem
What are we going to learn as the result of the proposed project that we do not know now?
Why is it worth knowing?
How will we know that the conclusions are valid?