chapter 2 class version a

Research Approaches and Methods of Data Collection

9/6/2012

Chapter 2

Roadmap

• Reading Quiz• Announcement about labs• Helpful resources update• Chapter 2 Material– Variables in quantitative research– Experimental research– Nonexperimental research– Qualitative research– Major data collection methods

Suggestion:

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www.psychologicalscience.org

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Reading Quiz:Your own paper. Name and date.

Write letter of correct answer for each question.

1. A variable that varies in type or kind is called a(n)a. Categorical variable c. Independent

variableb. Dependent variable d. Intervening variable

2. The strongest evidence for causation comes from which of the following research methods?

a. Experimental c. Correlationalb. Natural manipulation d. All of the above

Lab Announcement• If you are in one of these labs:

– PSYC 2950.302 Stephanie Womack Mon. 12:00 – 1:50 PM– PSYC 2950.303 James Garcia Thur. 4:00 – 5:50 PM– PSYC 2950.304 Elizabeth Jenkins Mon. 2:00 – 3:50 PM – PSYC 2950.311 Sean Lewis Thur. 6:00 – 7:50 PM

• Please consider switching to one of these labs:– PSYC 2950.310 Daniel Romero Wed. 5:30 – 7:20 PM– PSYC 2950.312 Megan Purser Fri. 10:00 – 11:50 AM

• Procedure:– E-mail your current lab instructor ASAP.– Psychology Dept. will e-mail to confirm if you are moved.

Helpful Resources

• Tutors:– Beth, Cesar, Jeff– Hours every day M-F in Terrill Hall 215– Info on Blackboard

• Librarian Pat Reese– “office hours” Mondays and Thursdays – Terrill Hall 383– Info on Blackboard

Now let’s dig in to Chapter 2 material!

• Overview of different research approaches

• In later chapters we will break down details of experimental and other research designs

Broad Categories of Research Design

• Quantitative – numerical data

• Qualitative – non-numerical data

• In psychology, the focus has traditionally been on quantitative

Variables in Quantitative Research

• Variable - Any characteristic of a phenomenon that can vary (differ) across organisms, situations, or environments.

Types of Variables

• Categorical Variable - comes in whole units or categories–Groups / categories

• Continuous Variable - forms a continuum and can be represented by fractional and whole units– Text calls this “Quantitative Variable”

Roles Played By Variables

• Independent Variable (IV) - an antecedent condition manipulated by the researcher

• Dependent Variable (DV) - measures the influence of the independent variable– Effect– Outcome measure

• See Table 2.1, p. 31 for a good overview

Examples• Study of the impact of different amounts of study time on

students exam grades.– What is IV?– What is DV?

• Study of the effect of stress on recall for studied list of words– What is IV?– What is DV?

Other Roles Played by Variables

• Mediating Variable

• Moderating Variable

• Extraneous Variable

Mediating Variable (Mediation)

Anxiety

Distracting Thoughts

Performance on Memory Task

Mediator operates between two other variables in a chain of causation.

Moderating Variable (Moderation)

• The relationship between an IV and DV depends on the level of some other variable

• Think interaction (ANOVA)

Moderation example

• client gender and therapy outcomes– Women better outcomes with female therapist– Men better outcomes with male therapist– Therapist gender is a moderating variable

• Do men or women have better therapy outcomes?

• It depends on the therapists’ gender

Extraneous Variable

• A.K.A. confounding variable or third variable• Competes with the IV in explaining the

DV/outcome• Example:– Ice cream sales positively correlated with violence– What’s going on?

TYPES OF QUANTITATIVE RESEARCH

Experimental Research Approach

• Approach to take when we want to investigate/determine causation

• Think “cause = experiment”

3 required conditions for claiming causation

1. Relationship conditionVariable A (IV) must be related to variable B (DV)

2. Temporal order conditionIf A is the CAUSE of B, changes in A must precede changes in B.

3. No alternative explanation conditionNo plausible alternative explanations for the cause of B exist.

The Psychological Experiment• An “Objective observation of phenomena that

are made to occur in a strictly controlled situation in which one or more factors are varied and the others are kept constant” (Zimney, 1961, p 18).

Elements of an Experiment

• Objective observation

• Of phenomena that are made to occur– Manipulation

• In a strictly controlled situation– One or more factors are varied– Others are kept constant

Example of an experiment

Treatment Posttest

Random Assignment to condition

XT Y

XC Y

Advantages of Experimental Designs

1. Causal Inference- Can attempt to determine cause

2. Control over extraneous variables

3. Ability to manipulate variables

Disadvantages of Experimental Design1. Only tests effects of manipulated variables

2. Can seem artificial/contrived

3. Inadequate method of scientific inquiry on its own

Experimental Research Settings• Field Experiments

• Laboratory Experiments

• Online Experiments

Field Experiment• conducted in a real-life setting

• Manipulate variables and control the influence of as many extraneous variables as possible.

• Observation in real world, not in a contrived lab setting.

Advantages• You may be able to observe the impact of a

variable in a real-world setting but not in a laboratory– Examples?

Laboratory Experiment• conducted in the controlled environment of a

laboratory.

• Able to control all or nearly all extraneous variables• Can manipulate one or more other variables of

interest.

Benefits• Potential better measurement ability in a lab

than in a field setting.

• Some things are not able to be observed in a field setting.

Internet Experiments• In order to still be an “experimental study”

something MUST be manipulated.

• Simply giving a survey to everyone and looking at correlations between measures is not “experimental”

• Benefits- Cheap, easy, fast, high power– Easy to access diverse populations– Bring experiment to participant

• Problems- lack of control, self-selection, dropout, multiple submissions

Does it all have to be Experimental?• No--Other research designs are commonly

used

• All of these tell us something unique

Quantitative vs. Qualitative• Quantitative research uses numerical data to

answer a research question

• Qualitative research uses non-numerical data to answer a research question–What is non-numerical data?–How can this help Experimental research?