1.4: Selecting a Research Method Flashcards
Types of Validity
External Validity and Internal Validity
External Validity
Refers to how generalizable the results of the experiment are.
For example, if the study on a drug is done on an Asian, middle-aged, average-weight man with high blood pressure, can the results be generalized to the population?
Internal Validity
When a study shows a truthful cause-and-effect relationship and the researcher is confident that the changes in the dependent variable were produced only by the independent variable.
A confounding variable hurts the internal validity because it creates lower confidence in the research conclusion.
Descriptive Research Method
Basic Purpose:
To observe and record behavior.
How Conducted:
Do case studies, naturalistic observations, or surveys.
Manipulated:
Nothing
Strengths:
Case studies require only one participant; naturalistic observations may be done when it is not ethical to manipulate variables; surveys may be done quickly and inexpensively (compared with experiments).
Weaknesses:
Uncontrolled variables mean cause and effect cannot be determined; single cases may be misleading.
Correlational Research Method
Basic Purpose:
To detect naturally occurring relationships; to assess how well one variable predicts another.
How Conducted:
Collect data on two or more variables; no manipulations.
Manipulated:
Nothing.
Strengths:
Works with large groups of data, and may be used in situations where an experiment would not be ethical or possible.
Weaknesses:
Does not specify cause and effect.
Experimental Research Method
Basic Purpose:
To explore cause and effect.
How Conducted:
Manipulate one or more variables; use random assignment.
Manipulated:
The independent variable(s).
Strengths:
Specifies cause and effect, and variables are controlled.
Weaknesses:
Sometimes not feasible; results may not generalize to other contexts; not ethical to manipulate certain variables.
