Theories, Hypotheses, and Correlational Studies Experiments: Determining Cause and Effect

Posing Developmental Questions What is a theory?

The Scientific Method Identifying questions of interest Formulating an explanation Carrying out research that either lends support to the explanation or refutes it

Hypothesis Can you think of a hypothesis related to grades assigned in this class? How could your hypothesis be tested?

Categories of Research Correlational research Experimental research

Correlational Studies: Finding a Correlation

Correlational Studies Correlation coefficient Mathematical score that ranges from +1.0 to Strength and direction of relationship between two factors Does not prove causality Does provide important information

Types of Correlational Studies Naturalistic observationEthnographyCase studiesSurvey researchPsychophysiological methods

Psychophysiological Methods Among the most frequently used psychophysiological measures: Electroencephalogram (EEG) Computerized axial tomography (CAT) scan Functional magnetic resonance imaging (fMRI) scan This fMRI shows activity in different regions of the brain.

Theories are systematically derived explanations of facts or phenomena. Theories suggest hypotheses, which are predictions that can be tested. Correlational studies examine relationships between factors without demonstrating causality, while experimental research seeks to discover cause-and-effect relationships.

Researchers measure age-related change by longitudinal studies, cross-sectional studies, and sequential studies.

Consider the following steps of the scientific method and rank them from first to last. a. Formulating an explanation. b. Carrying out research that either lends support to the explanation or refutes it. c. Identifying questions of interest.

In order to make a prediction in such a way that permits it to be tested, one must make a(n) _______________. a. theory b. hypothesis c. analysis d. judgment

A researcher stands near an intersection and writes down the time it takes for the lead driver to start up after the light turns green. The researcher records the gender and approximate age of the driver. This researcher is most likely engaged in _________. a. a case study b. naturalistic observation c. an ethnography d. survey research

Researchers using correlational methods typically use a study group and a control group to isolate cause-and-effect relationships. True False

Formulate a theory about one aspect of human development and a hypothesis that relates to it.

Experiments: Determining Cause and Effect Experiment Groups –Treatment/experimental –Control Variables –Independent –Dependent Random subject selection and assignment

Elements of an Experiment

So…true or false? A hypothesis predicts how dependent variables depends on the manipulation of the independent variable.

Why aren’t experiments always used? Logically impossibleEthically impossible

Choosing Research Settings Field study –Captures behavior in real-life settings –May allow participants to behave more naturally –May be used in correlational studies and experiments –Are often difficult to exert control over situation and environment Laboratory study –Holds events constant –Enables researchers to learn more clearly how treatment affect participants

Complementary Approaches Theoretical ResearchApplied Research

In experimental research: Developmentalists use controlled conditions to discover causal relationships between various factors.

Measuring Developmental Change Longitudinal studies –Measuring individual change Cross-sectional studies –Measuring people of different ages at same point in time Sequential studies

Using Developmental Research to Improve Public Policy Research findings can provide policymakers a means of determining what questions to ask in the first place. Research findings and the testimony of researchers are often part of the process by which laws are drafted. Policymakers and other professionals use research findings to determine how best to implement programs. Research techniques are used to evaluate the effectiveness of existing programs and policies.

Consider this… What are some policy issues affecting children and adolescents that are currently being debated nationally? Despite the existence of research data that might inform policy about development, politicians rarely discuss such data in their speeches. Why do you think that is the case?

A Quick Review: Research Techniques for Studying Development

Ethics and Research Ethical guidelines for researchers (SRCD and APA) Researchers must protect participants from physical and psychological harm. Researchers must obtain informed consent from participants before their involvement in a study. The use of deception in research must be justified and cause no harm. Participants’ privacy must be maintained.

The key to evaluating information relating to human development is to maintain a healthy dose of skepticism. No source of information is invariably, unfailingly accurate. So…what about the experts?

Consider the source.Evaluate credentials. Understand difference between anecdotal and scientific evidence. Find details of research-based advice.Do not overlook cultural context of information. Recognize that popular consensus does not guarantee scientific validity. Becoming an expert on experts

Experimental research seeks to discover cause- and-effect relationships. Experiments typically create two different conditions and use an experimental group and a control group. Researchers measure age-related change by longitudinal studies, cross-sectional studies, and sequential studies.

Scientific evaluation has shown that some practices supposedly based on developmental research are at best dubious and at worst invalid. The key to evaluating information relating to human development is to maintain a healthy dose of skepticism.

If a control group is not used in an experiment, the researcher cannot rule out the possibility that something other than the treatment produced the observed outcome. True False

In a(n) ______________, an investigator devises two conditions (treatment or control) and compares the outcomes of the participants exposed to those two different conditions in order to see how behavior is affected. a. experiment b. correlational study c. interview d. naturalistic observation

In a ______________research study, researchers are interested in measuring change in a single group of subjects over time. a. correlational b. cross-sectional c. longitudinal d. sequential

High school students who routinely do their homework while writing text messages to their friends, watching a program on television, and playing an electronic game in a window of their computer often claim that they are “multitasking” and are able to study more quickly and effectively this way. How might you design a basic experiment to test this claim?