Experimental vs.
Causal-Comparative
Studies
Topic 3
Experimental Study
 Study where treatments are given to observe their
effects
 Treatments – input or stimulus given by the researcher
 Not useful when a study would be physically, ethically,
legally, or financially impossible
Demographics
 Used to define groups in a study
 People with similar background characteristics such as
socioeconomic status
Causal-Comparison Study
 Non-experimental study
 Also called ex post facto study
 Characteristics of the study
 Observe and describe a current condition
 Look to the past to identify possible causes
 No treatment given
 More potential pitfalls – need to select comparison
groups carefully
Types of
Nonexperimental
Research
Topic 4
Nonexperimental Studies
 Purpose is to
observe/measure
 Causal-Comparative
Research
 Researcher does not try to
 Survey
change participants in any
way
 Census
 Case Study
 Longitudinal Research
 Correlational Research
 Research Methods
Causal-Comparative
Research
 Look to the past for causes of a current condition
 Interested in the causality, but an experiment is not
possible
Survey
 Also known as a poll
 Describes the attitudes, beliefs and behaviors of a
population
 Uses a sample or portion of the population being
studied
 With a good sample, generalizations about the
population may be drawn
Census
 Just like a survey, but all individuals in the population
participate instead of using a sample
Case Study
 Usually only one participant
 Often used in clinical psychology
 Focus on thorough knowledge of an individual over a
period of time
 In-depth questioning occurs
Longitudinal Research
 A study over a long period of time to trace
developmental trends
Correlational Research
 Researchers study the degree of a relationship of
quantitative variables
 Example: college admissions test and GPAs
 “Did those with high admissions scores tend to earn high
GPAs?”
Research Methods
 Quantitative
 Qualitative
 Historical
Quantitative Research
 Data is easy to quantify or put a number to
 Allows for statistical analysis
Qualitative Research
 Data is gathered through open-ended interviews
 Analyzed through major and minor themes in
responses
 Uses semi-structured interviews
 Core list of questions
 Deviating follow-up questions
Historical Research
 To understand the past
 Use facts and dates to understand the dynamics of
human history
 Driven by theories and hypotheses
 Hypotheses are evaluated using collected data
 Both qualitative and quantitative methods are used
 Will not be a focus of this text 