The Scientific Method

State/define Issue

Define the problem

Review the literature

Formulate the hypothesis

Select the research design then Collect and analyze data

Experiment Participant Observation

Survey Secondary data analysis

Scientific Research Method

Develop the conclusion and write the report

Ideas for further research

Scientifically, objectively and

logically to evaluate the facts

collected.

Psychological Research

Two forms of psychological research: Basic research seeks answers for

purpose of increasing knowledge.e.g. What role do the frontal lobes play in

memory?

Applied research seeks answers for specific problems.e.g. What types of memory strategies and

rehabilitation strategies are most effective for people with frontal lobe injuries?

The Scientific Method Operational Definition

statement of procedures (operations) used to define research variables

ie: intelligence may be operationally defined as “what an intelligence test measures”

Conceptual DefinitionDictionary definition Something formed in the mind; a thought or notion

The Scientific Method

Theory general explanation why behavior

occursHypothesis

testable prediction often derived from previous theory Example: I predict A will cause B I predict A will influence B

The Variables

Dependent Variable>what is being studied ?

value of DV depends on value of IVIndependent Variable> causes change in

DVConfounding Variable> unforeseen cause

“Hawthorne Effect”

Statistics in PsychologyPopulation –collection of all units or

elements of interest Sample – portion of population selected

to represent whole Replication

repeating procedures of research study with another sample of participants

can results be repeated?

Comparing Research Methods

Research Method Basic Purpose How Conducted What is Manipulated

Descriptive To observe and Case studies, surveys, Nothing(Goal: Describe) record behavior and naturalistic

observations

Correlational To detect naturally Computing statistical Nothing(Goal: Predict) occurring relationships; association, sometimes

to assess how well among survey one variable predicts responses

Experimental To explore cause Manipulating one or Independent(Goal: Explain) and effect more IVs and using variable(s)

random assignmentto eliminate preexistingdifferences among subjects

Scientific Data Collection1. Case Study indepth observation of

one person

2. Survey questionnaire about attitudes or behavior

3.Observation observing and recording behavior in situations

4. Experiment variables are manipulated to determine cause & effect

ExperimentExperimental Group

participants are exposed to independent variable (treatment)

Control Group participants do not receive independent

variable comparison group to see effect of independent

variable (treatment)Note: the measure (DV) is taken for both groups

Good Samples

Representative Sample a perfect reflection of population, only smaller in size

Random Sample fairly represents population because each member of sample had equal chance of being chosen

Experiment

Random Assignment assigning participants to experimental and control groups by chance

minimizes preexisting differences between those assigned to different groups

Experiment

Single-blind Procedure Research participants don’t know if they

are getting placebo or active agent.Double-blind Procedure

participants don’t know … research staff doesn’t know …(blind) Who is getting active agent vs. placebo?

Experiment

Placebo inert substance (e.g., sugar pill) instead of

an active agent (e.g., drug)

placebo administered to trigger same reaction as active agent (IV)

Placebo Effect any effect on behavior caused by a

placebo

VariabilityRange – distance between largest and

smallest score

Variance – index of average amount of dispersion using all scores in distribution

Standard Deviation – square root of variance; like variance, standard or typical distance of a score from mean

ReliabilityReliability-consistency of scores obtained

by same person when examined with same test on different occasions, time, places

If your height remained the same at your house, then at school, & then at the doctor’s office, it would be reliable. You would not trust a measurement device that varied greatly.

Analysis of Data

Types of statistics Descriptive – Arithmetic formulas for

summarizing and describing research data Inferential – Used for analyzing data to test

hypothesesIs the difference meaningful?Statistical significance

Central Tendency

Mean – (average) computed by summing all scores in set, dividing by total number of scores

Median – midpoint of distribution; divides distribution into 2 equal halves

Mode – score with greatest frequency

Correlation Coefficient (r) (Pearson r)

measure that shows extent to which two variables change together

permits investigators to see link or association between variables

good for prediction Note: correlation does not imply causation!

Correlations refer to looking at relationship between two variables without manipulating

Is this causation or correlation?

The more soy sauce sold in Newnan the higher church attendance.

A leads to B

1+1=2

You jump because I pinched you.

Normal Curve

0

0.5

1

1.5

2

2.5

3

3.5

-3SD -2SD -1 SD Mean +1 SD +2 SD +3 SD

68%

95%

99%

Mesokurtic

r = -.09

4.50

6.50

8.50

10.50

12.50

14.50

2.40 2.90 3.40 3.90 4.40

GPA

Sh

oe

siz

e

No Correlation

Positive Correlation

Commuting distance of

workers

Worker tardiness

Strong Positive Correlation

(11 and 21)

Negative Correlation

Amount of Work

Experience

Waste Produced

Strong Negative Correlation

Experimental Issues Controls important for determining causality

only difference between experimental & control groups is presence or absence of IV.

Placebo effects represent changes in behavior that are related to expectations of a treatment. placebo effects are controlled by a “blind”

control group Experimenter bias expectations influence

participant’s behavior. example: Clever Hans, the horse who could do

math can be controlled using double blind proceduresHindsight Biasbelief, after learning an outcome, that one would have foreseen it “I-knew-it-all-along” phenomenon

Ethical Guidelines

APA Guidelines Truth in reporting Treatment of participants

Special guidelines for I/O psychologists Legal and profession obligations Management vs. employees

Ethical Issues in ResearchRespecting the rights of human research

participants involves: Informed consent an explanation of study and

responsibilities of experimenter and participant.

Confidentiality study information must be maintained.

Debriefing explaining research process to participants at end of study.

Deception involving participants must be justified.

APA Ethical Guidelines (animals)

“appropriate consideration of [the animal’s] comfort, health, and humane treatment.”

Animals may not be subjected to “pain or stress” when alternative procedure is available.