Variables and Hypotheses
8/29/2013
Readings
• Chapter 1 The Measurement of Concepts (14-23) (Pollock)
• Chapter 2 Measuring and Describing Variables (Pollock) (pp.28-31)
Backing Up Your Data
• Save the Information from the CD onto another media– Flash Drive
– Edshare
• These are just data files, not aprogram
We Will Use the Full Version
Make Sure you move these files
The Files that We Will use• Data Files on the Pollack CD
• GSS2008.SAV- the 2008 General Social Survey Dataset– n=2023 – 301 variables
• NES2008.SAV- the National Election Study from 2008. n=2323 – 302 variables
• STATES.SAV- aggregate level data for the 50 States. N=50 – 82 Variables
• WORLD.SAV- aggregate level data for the nations of the world. n=191 – 69 Variables
OPPORTUNITIES TO DISCUSS COURSE CONTENT
Office Hours For the Week
• When– Friday 10-12– Tuesday 8-12– And by appointment
• Last day to change any class is friday
Course Learning Objectives
1. Students will learn the research methods commonly used in behavioral sciences and will be able to interpret and explain empirical data.
2. Students will learn the basics of research design and be able to critically analyze the advantages and disadvantages of different types of design.
CONCEPTSThe First Steps in Measurement
Concepts
• The words we use to describe political and social phenomenon
• Conceptual Definition- States the concept in unambiguous terms
• The Operational Definition- setting your concept in a way that can be measured
THE SECOND STEP: VARIABLESMeasurement
What are Variables
• These are simply measured concepts
• Giving a concept value is called operationalization
• Good variables take on all values of a concept
• Why variables are important
How We Operationalize Fancy
• Fancy canned tomatoes must have a drained weight not less than 66% of the capacity of the container
• U.S. Grade B or U.S. Extra Standard must have a drained weight of not less than 58% of the capacity of the container
Variable Measurement
• constants
• Dichotomous Variables
• The rest
Dichotomous Variables
The Dependent Variable
• The variable in a relationship you want to explain. The Y variable
• There is only one of these in a relationship
• It changes in response to an independent variable
The Independent variable
• Variables that that cause change in the dependent variable
• The (X) variable
• You may have more than 1 of these
The Relationship Between them
Telling the Difference between I.V.’s and the D.V.
Additive Relationships
• Explaining a Dependent variable with more than 1 independent variable is called an additive relationship!
• Most Social Science relationships involve many i.v.’s…. Why?
Causes of Cancer
Additive Relationships
Independent Variables at Play
Why the Decline?
Antecedent and Intervening Variables
Antecedent• Come before the
independent variable
• Things like Demographics
Intervening• Come in-between the IV
and the DV
• Temporal events
How they can influence relationships
A Spurious Relationship• What antecedent variable might be at play?
Intervening Variable
UNITS OF ANALYSISHow we measure our Variables
Units of analysis
• The unit about which information is collected and that provides the basis of analysis
• Each member of a population is an element
• Why they are important?
Individual Unit
• Studying an individual case or example
• A single survey response
• People, congressmen, presidents, etc
Aggregate Data
• A collection of individual level units
• Often measured in percentages
Counts can distort
The Poor over Time
Immigration over time
Health Care Access
FALLACIES MADE WITH DATA
Ecological Fallacy
• this arises when an aggregate/ecological level phenomenon is used to make inferences at the individual level.
• Taking statewide data and applying to individuals
• Does everyone in MS go to church?
An Example
• On Mr. Burns Wanting to bowl: "Call this an unfair generalization if you must, but old people are no good at everything." Moe the Bartender from the Simpsons
The Exception Fallacy
• taking one person's behavior, attributes, etc and applying it to an entire group
• Using 1 example to define group behavior
Perceptions in Europe
Examples from Texas Style
How We View Others
HYPOTHESES
What Is a Hypothesis
• An educated Guess
• These are explicit Statements
• They Try to explain a relationship
• But they are only tentative until tested
The Null Hypothesis
• The Statement of No Relationship
• What we want to disprove
• The Basic start of research
H0
On Stating the Null “there is no relationship between the
independent and dependent variable”
Correlative Hypothesis
• “there is a relationship between x and y”
• A very weak statement
Positive Hypothesis
• A directional hypothesis
• “as the independent variable increases, the dependent variable increases”
Positive Relationship
On Stating a Positive relationship: There is a positive relationship
between my independent variable (how much I drank) and dependent
variable (the better you look)
Negative Relationship/Hypothesis
• “As the independent variable increases, the dependent variable decreases”
• Also called an inverse hypothesis
Minimum Wage
On Stating a negative hypothesis: There is a negative (inverse) relationship between “beers
drank” (independent) and “grade” (dependent variable)