Research in Psychology

Is Empirical (based off observation)

Measures and Describes( psychological constructs and operational

definitions) Makes a Prediction

(formulates a hypothesis about the relationship between 2 or more variables)

Suggests an application (understanding allows control over our environment)

Theories, Hypotheses, and Research

Theories (from the specific to the general)

Hypotheses (from the general to the specific)

Research ( a term for the multiple ways a hypothesis can be tested)

Steps in Scientific Research

1) Establish a testable hypothesis (operational definition must be clear and precise)

2) Design the Study (how you will test and measure the variables of interest)

3) Collect the Data (Could be though direct observation, questionnaires, or behavioral tests)

4) Analyze Data and Suggest an Application (statistical analysis and relevance of research)

5) Report the findings (writing a research report and journal submission)

Experimental Research

Establishes Cause and Effect Independent Variable (IV): is manipulated

Dependent Variable (DV): is measured

Experimental Group : receives the (IV)

Control Group: receives nothing or placebo

Experimental Research Population (random selection)

Sample (random assignment)

Extraneous Variables: are controlled• Selection bias (random selection)• Assignment bias (random assignment) • Experimenter bias (double-blind study)• Novelty effects (field study)

Confounding Variables: have an effect on the (DV)

Alleviation of Depression = Dependent VariableBetween-Subjects Experimental Design

Experimental Group

Receives the IV (antidepressant)

Control Group

Receives nothing (placebo)

Identify the (IV) and the (DV)

• A researcher is conducting a study to see if room temperature influences learning.

• Of 100 individuals with obsessive-compulsive disorder (OCD), 50 receive 8 weeks of an experimental drug for OCD, while 50 are placed on a waiting list for 8 weeks. At the end of the 8 weeks, all 100 individuals are given psychological tests to assess their level of OCD.

Variations in Experimental DesignsWithin-Subjects Experimental Design

Some experimental designs do not compare groups. (no random assignment)

All members of the sample participate in both control and experimental conditions.

A researcher is evaluating the effects of a study skills class on the GPA scores of college Freshman.

Variations in Experimental DesignsSingle-Subject Experimental Design

Researchers may choose to experiment with a single Participant. (no random selection or random assignment)

Statistical Analysis

The Null Hypothesis (accept or reject)

Type I Error: rejecting a true null hypothesis

Type II Error: accepting a false null hypothesis

The Alpha Level: the probability of chance occurrence• Low Alpha (.01) increased risk of type II error• High Alpha (.05) increased risk of type I error

Advantages and Disadvantages of Experimental Research

Advantages It is the only form of

research that can establish cause and effect.

Experiments allow the researcher precise control over variables.

Disadvantages Experiments are often

artificial. Some experiments cannot

be conducted due to ethical concerns.

Correlational Research

A Non-experimental form a research that shows a directional relationship between variables.

Correlational Coefficient (numerical value that determines the strength of a relationship between variables between -1 and +1)

Positive Correlation High scores on X are related to high scores on Y, and low scores on X are

related to low scores on Y.

Years Smoking

X

Risk of Cancer

Y

Years Smoking

X

Risk of Cancer

Y

Negative Correlation High scores on X are related to low scores on Y, and low scores on X are

related to high scores on Y.

Amount of hours of cocaine sleep

x

Amount of hours of cocaine sleep

xY

No Correlation

A correlation coefficient of (0) indicates there is no relationship between variables.

Correlational Coefficient

Negative Correlation Positive Correlation

-1_______________________0______________________+1 Strength of Relationship

Increasing Increasing

Advantages and Disadvantages of Correlational Research

Advantages It allows researchers to

study variables that would be unethical to manipulate.

Researchers can study variables as they exist naturally.

Disadvantages Correlations are not able to

show cause and effect. (no manipulation of the (IV)

They provide little control over extraneous variables.

The direction of the relationship is unclear.