Research Basics

Lecture notes

Theory

* Summarizes existing empirical knowledge of the phenomenon
* Organizes knowledge in terms of laws
* Proposes an explanation for the phenomenon
* Serves as a basis for making predictions

**Example: James-Lange theories of emotions**

* Emotional stimulus → Physiological response → Affective experience

Hypothesis

Reasonable prediction about research results based on a theory

**Example: facial feedback hypothesis**

* Pen-in-mouth

Construct

A complex or abstract idea relevant to the research (i.e., happiness)

Operational Definition

A working definition of a construct based on how it is measured in a study

* Example: Discrete Emotions Questionnaire (the degree to which participants experienced happiness, satisfaction, liking, and enjoyment during the study)

Variable

A quantity or quality that varies across people or situations

Quantitive Variable

A quantity that is typically measured by assigning a number to each individual

Categorical Variable

A quality that is typically measured by assigning a category label to each individual

Simple Random Sampling

Every member of the population has an equal chance of being selected for the sample

Convenience Sampling

The samples consists of individuals who happen to be nearby and willing to participate

Measured Variables

Variables whose levels are simply observed and recorded, also called dependent variables in Experimental methods

Manipulated Variables

Variables whose levels are controlled by a researcher, also called independent variables in Experimental methods

Test-retest Reliability

Known as *r*

* r = -1 is a negative correlation
* r = 1 is a positive correlation
* r = 0 is no correlation

Interrater Reliability

The extent to which two raters agree with each other, *kappa*

Internal Reliability

The extend to which different items go well together, Cronbach’s alpha

Types of Measurement Validity

* Content validity
* Criterion validity
* Construct validity
* Convergent validity
* Discriminant validity

Content Validity

The measure captures what you want to capture from its conceptual definition

* Theory

Criterion Validity

The measure correlated with a relevant outcome

* Predictive
* Concurrent

Construct Validity

* Convergent validity – the measure correlates with other measures of similar construct
* Discriminant validity – the measure does not correlate with measures of dissimilar constructs

Three Common Types of Claims

* Frequency – claims about how much or how many
* Association – claims about covariance or difference
* Causality – claims about cause-and-effect or impact

Association vs. Causality

Association:

* Is at higher risk for
* Is more/less likely to
* Is linked to

Causality:

* Causes
* Promotes, worsens, increases, reduces
* Affects
* Prevents, fight