Psychology 633 –
Scientific Method & Research Strategies

I.  Goals of Science:

(1) Discover Regularities; (2) Describe Behavior; (3) Discover Laws; (4) Search for Causes; (5) Develop Theories

 

II.  Steps of the Scientific Method

Step 1: Observe Behavior or Other Phenomena

Step 2: Form a Tentative Answer or Explanation (Hypothesis)

Step 3: Use the Hypothesis to Generate a Testable Prediction

Step 4: Evaluate the Prediction by Making Systematic, Planned Observations

Step 5: Use the Observations to Support/Refute/Refine the Original Hypothesis

 

 

III.  What is a hypothesis?

 A testable prediction about the relationship between two or more variables

Questions to Ask About a Potential Hypothesis

1. Can it be proven wrong?

Operational definitions?

Is the prediction specific?

2.  Can your hypothesis be supported?

Are you predicting that you will find an effect or a difference? (Your results can never prove the null hypothesis)

3.  Are there logical reasons for expecting the prediction to be correct?

Based on or predicted by theory?

Consistent with past research findings?

Follow common sense?

4.  Would the results of your test of the hypothesis be relevant to

previous research?

existing theory?

a practical problem?

5.  Is it practical and ethical to test your prediction?

physical and financial resources?

access to participants/subjects from population of interest?

would your test cause physical or psychological harm to participants/subjects? justifiable?

appropriate approval from IRB and/or school district?

 

What is the difference between a theory and a hypothesis?

 ****descriptive vs. causal hypothesis

**** theory-driven vs. data-driven hypothesis

 

  theory arises from repeated observation and testing. Incorporates facts, laws, and tested hypotheses that are widely accepted.

IV. Research Strategies

            A. Descriptive Strategy

 Focus is on describing (as opposed to explaining or predicting).

Descriptive studies are numerically descriptive.

 
           B. Correlational Strategy

Measuring two different variables for each participant in order to describe the relationship between the two variables. 

The variables are usually measured as they occur naturally—without any attempt to manipulate or control them.

            C. Experimental Strategy

The experimenter manipulates at least one IV. A DV is used to measure the effects of the IV.

4 characteristics of true experiments:

1 – MANIPULATION

2 – MEASUREMENT 

3 –COMPARISON 

4 – CONTROL

 

The Basic Components of an Experimental Research Study

 

            D. Quasi-Experimental Strategy

Aim to establish a tentative cause and effect relationship between two variables but cannot satisfy all of the strict requirements needed for a true experiment (often cannot not meet all of the above requirements in a natural settings). Introduce some treatment or manipulation.

Uses some of the rigor and control used in true experiments. But in some way, lack the control found in true experiments (usually lack random assignment of participants to conditions), so ability to draw a causal inference is impaired

 

        E. Non-Experimental Strategy

Two different groups are involved, but the researcher does NOT manipulate a variable to create the groups

No manipulation, naturally occurring groups that differ qualitatively, we make a comparison on the DV. Sometimes called causal comparative, which is a popular non-experimental strategy.

V. Validity

How well does the study answer the question it was intended to answer?

**A researcher's ultimate goal: “This is what happened, and this is what it means.”  Any factor that raises doubts about the research results or about the interpretation of the results is a THREAT TO VALIDITY.

      A. Internal Validity

Extent to which other causes are ruled out—extent to which the difference in behavior can unambiguously be attributed to the manipulation 

B. External Validity

Extent to which we can generalize the results of a research study to people, settings, times, measures, and characteristics other than those used in that study.

   

A cold, hard fact:

It is impossible for a study to totally eliminate all threats to validity. Each study is a set of decisions and compromises. Often there's a trade-off between internal and external validity. Therefore, a single study can never "prove" anything on its own. We need to get converging evidence. Also, we must always be critical consumers of research and make our own decisions about validity and quality of the research.

 

***For thought & discussion

1) What is a research question you have?  Try to state it in the form of a question you would attempt to answer in your study.

2) Which design is best suited to answer your question?  Why?