Chapter 2 Psychology’s Scientific Method RESEARCH METHODS Chapter 2 Psychology’s Scientific Method

4 goals of psychology Describe behavior Predict behavior Explain behavior Control behavior

5 steps of the Scientific Method Observing some Phenomenon Formulating Hypotheses and Predictions Testing through Empirical Research Drawing Conclusions Evaluating the Theory

5 STEPS OF THE SCIENTIFIC METHOD 1. Observing some Phenomenon Asking questions Variables 2. Formulating Hypotheses and Predictions

5 STEPS OF THE SCIENTIFIC METHOD 3. Testing through Empirical Research: Choose your research method Descriptive Research: describes some phenomenon Naturalistic Observation Survey/ Interview Psychological/ Physiological Tests Case Study Archival Research Correlational Research: shows relationships Experimental Research: shows cause and effect

5 STEPS OF THE SCIENTIFIC METHOD 3. Testing through Empirical Research: Choose your research design (NOT for Experimental Research) Cross-sectional: Study participants of different age groups at the same time. Advantage: quicker, less costly Disadvantage: cohort effects, sample variability Longitudinal: Study a particular group of participants over a prolonged period of time. Advantage: more in-depth investigation, shows change over time Disadvantage: more costly, dropout/death

5 STEPS OF THE SCIENTIFIC METHOD 4. Drawing Conclusions Replication Descriptive/Inferential Statistics 5. Evaluating the Theory Meta-analysis Submitting results for publication

Introductory Terminology for Scientific RESEARCH Variable: Any measurable condition that is controlled/observed in a study; anything that can change. Theory: A broad idea or set of closely related ideas that attempt to explain observations and to make predictions about future observations. Hypothesis: An educated guess that derives logically from a theory; a prediction that can be tested. Operational Definition: An objective description of how a variable is going to be measured and observed. Participants or subjects: The organisms whose behavior is systematically observed in a study.

Research Methods Descriptive Research: Naturalistic Observation Survey/Interview Case Study Archival Studies

Naturalistic Observation Description: Observing the participant in their natural habitat without interaction Advantages Disadvantages Realistic picture of behavior Good to start when little is known about a phenomenon Difficult to remain unnoticed or unobtrusive Time consuming

Survey/Interview Description: Use of questionnaires to gain insight on an individual’s attitudes or beliefs Advantages Disadvantages Gathers data of difficult to observe behaviors Large sample size Cost effective Relatively easy Wishful Thinking Memory Lapses Social Desirability Bias Response Set Wording Effect

Case Study Description: An in-depth investigation on an individual or cohort (small group) Advantages Disadvantages In-depth investigation Helps formulate theories Unique cases Subjectivity Researcher bias Lack of generalizability

Archival research Description: Extracting evidence from original records or other researcher’s findings Advantages Disadvantages Researcher can not change data Cost effective Researchers have little to no control over information Credibility of sources

Research Methods 2. Correlational Research

Correlational Research Research that examines the relationships between variables, whose purpose is to examine whether and how two variables change together. There is NO manipulation of variables CANNOT imply a cause and effect relationship between the variables

Correlational Research CORRELATION DOES NOT EQUAL CAUSATION!

Correlational Research A local police chief in a small Midwestern town finds that as ice cream consumption increases, the crime rates increases. As people eat less ice cream, the crime rate decreases. The police chief concludes that ice cream causes crime. Scientists have linked television-watching with childhood obesity. According to a study in the Journal of the American Academy of Pediatrics, the degree of obesity rises 2 percent for each hour of television viewed per week by those aged 12 to 17. Scientists conclude that TV watching makes you obese.

CORRELATIONAL research Third variable problem: The circumstance where a variable that has not been measured accounts for the relationship between two other variables.

Correlational Research Research study designed to determine the degree to which two variables are related to one another When two variables are related to each other, they are co - related A correlation is the numerical index of degree of relationship Correlation are expressed as a number between 0 and 1 Can be negative or positive (-1 to +1) Numbers closer to 1 (+ or -) indicate a stronger relationship A correlation exists when two variables are related to each other. The correlation coefficient is a numerical index of the strength and direction of association between two variables. A correlation is expressed as a number between 1 and 0, and the number may be positive or negative. The closer to 1 the number is, whether +1 or –1, the stronger the relationship between the variables…for example, a correlation of .17 is pretty weak, while a correlation of -.89 is pretty strong. The positive/negative dimension of the correlation coefficient expresses the direction of the relationship. If two variables are positively correlated, they co-vary in the same direction…as scores on one variable go up, scores on the other variable go up too…if two variables are negatively correlated, the variables co-vary in the opposite direction…as one goes up, the other goes down.

Correlational Research

CORRELATIONAL research How to read a Correlation Coefficient: Correlation Coefficient: A statistical measure of the relationship between two variables.

CORRELATIONAL research Strength

CORRELATIONAL research Direction

CORRELATIONAL research POSITIVE CORRELATIONS As the value of one variable increases (or decreases) so does the value of the other variable. The closer the correlation coefficient is to +1.0, the stronger the relationship. A perfect positive correlation is +1.0 Direct relationship Height Weight

CORRELATIONAL research NEGATIVE CORRELATIONS As the value of one variable increases, the value of the other variable decreases. The closer the correlation coefficient is to -1.0, the stronger the relationship. A perfect negative correlation is - 1.0 Inverse relationship Temperature Sweater Sales

CORRELATIONAL research ZERO CORRELATION There is no relationship whatsoever between the two variables. The closer the correlation coefficient is to 0, the weaker the relationship. No relationship Hours Spent Brushing Teeth Kitten Perpetrated Homicides

Correlational Research Coefficient of Determination: Percentage of variation in one variable that can be predicted based on the other variable. Square the correlation coefficient by itself Ex: .70² = .70 * .70 = .49 = 49% .24² = .24 * .24 = .057 = 5.7%

CORRELATIONAL research Description: determines the degree to which two variables are related to one another Advantages Disadvantages No manipulation of variables Allows large populations to be studied at one time Cost effective and Quick Enables investigation of difficult variables to study CANNOT show cause and effect Does not show the reason for the relationship