Research MethodsResearch MethodsLecture 2Lecture 2

Non-experimental and Experimental Research Approaches

Chapters 2 & 3

Research Research Designs/ApproachesDesigns/Approaches

Type Purpose Time frame

Degree of control

Examples

Experi-mental

Test for cause/

effect relationships

current High Comparing two types of treatments for anxiety.

Quasi-experi-mental

Test for cause/

effect relationships without full control

Current or past

Moderate to high

Gender differences in visual/spatial abilities

Research Research Designs/ApproachesDesigns/Approaches

Type Purpose Time frame

Degree of control

Examples

Non-experimental - corre-lational

Examine relationship between two variables

Current (cross-sectional) or past

Low to medium

Relationship between studying style and grade point average.

Ex post facto

Examine the effect of past event on current functioning.

Past & current

Low to medium

Relationship between history of child abuse & depression.

Research Research Designs/ApproachesDesigns/Approaches

Type Purpose Time frame

Degree of control

Examples

Non-experimental -corre-lational

Examine relat. betw. 2 var. where 1 is measured later.

Future -predictive

Low to moderate

Relat. betw. history of depression & development of cancer.

Cohort-sequen-tial

Examine change in a var. over time in overlapping groups.

Future Low to moderate

How mother-child negativity changed over adolescence.

Research Research Designs/ApproachesDesigns/Approaches

Type Purpose Time frame

Degree of control

Examples

Survey Assess opinions or characteristics that exist at a given time.

Current None or low

Voting preferences before an election.

Quali-tative

Discover potential relationships; descriptive.

Past or current

None or Low

People’s experiences of quitting smoking.

Non-experimental Research Non-experimental Research DesignsDesigns

Describes a particular situation or phenomenon.

Hypothesis generatingCan describe effect of implementing actions

based on experimental research and help refine the implementation of these actions.

Correlational DesignCorrelational Design

Measure two variables– Study methods and grade-point average

Determine degree of relationship between them– Correlation coefficient (e.g., r = 0.50)

Allows description and prediction of the relationship

Correlational StudiesCorrelational StudiesType of descriptive research design

– Advantage is that it can examine variables that cannot be experimentally manipulated (e.g., IQ and occupational status).

– Disadvantage is that it cannot determine causality.

– Third variable may account for the association.– Directionality unclear

Origins of the Correlation Origins of the Correlation CoefficientCoefficient

64” 65” 66” 67” 68” 69”

70” 2 4 5 5

69” 2 3 5 8 9 9

68” 3 6 10 12 12 2

67” 7 11 13 14 13 10

66” 6 8 11 11 8 6

65” 3 4 6 4 3 2

Children’s height

Par

ent’

s he

ight

Correlation between parent’s height and children’s height

Correlation ScatterplotCorrelation Scatterplot

Strong Positive Relationship

Correlation ScatterplotCorrelation Scatterplot

Strong Negative Relationship

Correlational DesignsCorrelational Designs

What are some correlational studies that you can do?

Ex Post Facto StudyEx Post Facto StudyVariable of interest is not subject to direct

manipulation but must be chosen after the fact.

E.g., Define two groups of people according to a certain characteristic (e.g., history of trauma) and measure how they respond in terms of anxiety to a certain stimulus (e.g., watching violent film).

Limitation – self-selection bias, cohort effects may explain the effect.

Personality and Hypertension,Personality and Hypertension,Effect of Hypertension AwarenessEffect of Hypertension Awareness

Hypertens ion S tudy - S creened 10 ,500 E m ployees

P erson a lityS tu d y

2 n d B PS creen

M atch edN orm oten s ive

5 th B P S c reen5 m on th s

M ean D B P > = 9 0 m m H g

4 th B P S c reen4 m on th s

3 rd B P S c reen3 m on th s

P erson a lityS tu d y

2 n d B P S c reen2 -3 w eeks la te r

1 s t B P S c reenH yp erten s ive D B P

Personality and Hypertension: Effect Personality and Hypertension: Effect of Hypertension Awarenessof Hypertension Awareness

Variable Group 1

Aware

Hyper-tensive

Group 2

Normo-tensive

Group 3

Unaware

Hyper-tensive

Group 4

Normo-tensive

% Male 75 75 89 89

Age

Mean* (SD)

46.2

(9.2)

46.2

(8.2)

46.4

(8.3)

45.8

(8.0)

SBP/DBP

Mean* (SD)

135.1/

93.9

(9.2/5.1)

118.7/

76.3

(11.5/5.5)

135.8/

93.8

(8.2/3.4)

118.5/

75.7

(10.3/4.8)

Personality and Hypertension: Effect Personality and Hypertension: Effect of Hypertension Awarenessof Hypertension Awareness

Variable Group 1

Aware

Hyper-tensive

Group 2

Normo-tensive

Group 3

Unaware

Hyper-tensive

Group 4

Normo-tensive

Neuro-ticism

Mean* (SD)

12.0

(5.3)

9.3

(5.3)

9.7

(4.8)

9.5

(4.6)

Type A

Mean* (SD)

0.79

(8.5)

-3.0

(9.4)

-2.0

(9.4)

-2.6

(8.2)

* Group 1 > Group 2 & Group 3 (p < 0.01)

Personality and Hypertension:Personality and Hypertension:Effect of Hypertension Effect of Hypertension

AwarenessAwareness

0123456789

1011121314

Neuroticism

Aware Hyper

Normot

Unaware Hyper

Normot

Aware hypertensive > normotensive & unaware hypertensive,P < 0.001

Personality and Hypertension:Personality and Hypertension:ConclusionConclusion

Do hypertensives have a different personality than those with normal blood pressure?– No, because the unaware hypertensives did not

differ from the normotensives.

Why did the aware and unaware hypertensives differ?– Possible explanations?

Personality and Hypertension:Personality and Hypertension:ConclusionConclusion

Awareness of hypertension status confounds assessment of the association between personality characteristics and hypertension.

– Due to hypertension labeling effect; or– Due to self-selection bias

Cross-Sectional Study Cross-Sectional Study DesignsDesigns

Compares groups at one point in time– E.g., age groups, ethnic groups, disease groups.

Advantage is that it is an efficient way to identify possible group differences because you can study them at one point in time.

Disadvantage is that you cannot rule out cohort effects.

Longitudinal DesignLongitudinal Design Gathers data on a factor (e.,g. confidence) over time. Advantage is that you can see the time course of the

development or change in the variables – Confidence increasing with age.– Confidence increasing at a faster rate in the 30’s than the

40’s.– Confidence decreasing in the 50’s and 60’s.

Disadvantage is it is costly and still subject to bias

Cohort-Sequential DesignCohort-Sequential Design Combines a bit of the cross-sectional design and

longitudinal design– E.g., Different age groups are compared on a variable over

time.

Advantage – very efficient and reduces some of the biases in the cross-sectional design since you can see the evolution of change over time.

Disadvantage – cannot rule out cohort bias or the problem of the ‘unidentified’ third variable accounting for the change.

Naturalistic ObservationNaturalistic ObservationAims to unobtrusively observe behaviour in

the natural setting.Observing in the natural setting enables one

to minimize or eliminate the problem of artificial behaviour in response to being studied (i.e., reactivity effects).

One variation is being a participant observer (e.g., undercover agent).

Naturalistic ObservationNaturalistic Observation

Advantages– Observe the natural phenomena (not artificial)

Disadvantages– Observer bias– Reactivity in subjects– Ethics

Meta AnalysisMeta Analysis(Glass 1976)(Glass 1976)

Quantitative approach to integrate and describe results across a range of independent studies.

Enables you to combine the probability (p) value for statistical tests over a number of studies.

Enables you to determine the effect size of the independent variable (e.g., treatment group) across studies.

Survey ResearchSurvey ResearchCollecting standarized information from

people using an interview or self-report format.

Typically survey knowledge or opinions.To standarized the information one uses a

questionnaire with set questions.Ideally the questionnaire has been validated.Representativeness of the sample is very

important.

Survey MethodsSurvey MethodsInterviews

– Advantage - Comprehensive, ensure participant understands the question, minimizes missing data, enables clarification of unclear responses

– Disadvantage – expensive, people more like to refuse participation, can be risky for interviewer, interviewer may bias the responses.

Types of Survey MethodsTypes of Survey MethodsFace-to-face interviews

– Expensive and time-consuming

Telephone interviews– Need to use random-digit dialing to reach both

listed and unlisted numbers.

Mail– Return rate is usually low (20-30%).

Types of QuestionsTypes of QuestionsOpen-ended

– E.g., Can you tell me about your typical experience with dating?

Close-ended– E.g., How do you typically meet someone to date?

Introduced by someone Social event In university class or place of work At a bar Through sports or other athletic events

SamplingSamplingPopulation is everyone in your population

of interest.Sample is some proportion of the

population.Haphazard sampling – convenience sampleRandom sampling

– There is always some degree of sampling error.

Qualitative MethodsQualitative MethodsMultimethod approach to studying people

in their natural environment– It is interpretive – researcher has to make sense

of the data– Multimethod – can use interviews,

photographs, natural observation, archives, etc.– It is typically conducted in person’s natural

environment.Valuable to use when phenomenon not fully

defined.

Qualitative MethodsQualitative MethodsLimitationsLimitations

Participant’s observations and accounts can be biased. For example, filtered by his/her style of expression, gender, social class, race, age, ethnicity, etc.

People are seldom able to provide a true and full account of their experience.– Defensive– Lack insight– Unaware

Qualitative MethodsQualitative Methods

Transcripts

Experimental DesignsExperimental DesignsExamines differences between experimentally

manipulated groups or variables (e.g., one group gets a certain drug and the other gets a placebo).

At minimum, experimental (independent) variable has two levels (e.g., drug vs. placebo).– Advantage is that you can determine causality.– Disadvantage is cost and many variables cannot

be experimentally manipulated (e.g., smoke exposure over time).

Experimental DesignsExperimental DesignsFour Canons for Identifying Four Canons for Identifying

CausalityCausalityMethod of Agreement –

– Observe the element common to several instances of the event

– Problem is you may inadvertently overlook a significant variable.

Method of Difference –– Identify the different effects produced by two

situations that are alike in all ways but one.– Fairly robust and strong method.

Experimental DesignsExperimental DesignsFour Canons for Identifying Four Canons for Identifying

CausalityCausalityJoint methods of agreement and difference

– Observe the element common to several instances of the event

– Form hypothesis based on observations– Test hypothesis using method of difference

Method of Concomitant Variation –– Identify the different effects produced by more

than two situations that are alike in all ways but one.

– E.g., Compare two active drugs to a placebo

Experimental DesignExperimental Design

Because it is so difficult with human behaviour to demonstrate causation unequivocally, some argue that a theory or prediction can only achieve the status of “not yet disconfirmed” (Popper, 1968).

Our scientific efforts are directed at finding the causal factors rather than ‘the cause’ per se.

Psychological Experiment:Psychological Experiment:Is ObjectiveIs Objective

Researcher strives for freedom from bias.Recognize that:

– Mistakes can occur– Carefully scrutinize all steps of the experiment to

identify where mistakes are likely.– Take the steps necessary to minimize error.

Psychological Experiment:Psychological Experiment:Focuses on a PhenomenonFocuses on a Phenomenon

This is a publicly observable behaviour.– Actions– Appearances– Verbal statements– Responses to questionnaires– Physiological responses.

Psychological Experiment:Psychological Experiment:Is Done Under Strictly Controlled Is Done Under Strictly Controlled

ConditionsConditionsEliminate all factors that could influence the

outcome other than the factor being manipulated.

Control is needed to infer causation.All conditions are kept constant except one;

the manipulated variable.The variable of interest is varied in order to

test its effect.

Experimental MethodExperimental Method

Advantages– Strength with which causal relationships can be

inferred.– Ability to manipulate one or more variables.– Proven to be a very useful and robust scientific

method (i.e., withstood the test of time).

Experimental MethodExperimental Method

Disadvantages– Tight controls often produce artificial

conditions that could limit the generalizability of the findings (i.e., internal vs. external validity trade-off).

– Time consuming.– Expensive.– Human behaviour is very complex and cannot

be fully studied using experimental methods.

Experimental Method:Experimental Method:Threats to Internal ValidityThreats to Internal Validity

Learning or practice effects– Scores on a measure change on repeat testing

because participant has more familiarity with the measure and so answers more truthfully.

Natural history effects– Something happens in the social background

(e.g., society because more affluent generally) and this influences the participant’s responses.

Maturation– Natural developments in the participant account

for the changes (e.g., getting older).

Experimental Method:Experimental Method:Threats to Internal ValidityThreats to Internal Validity

Regression to the mean– High scores generally move down toward the

mean and low scores move up.

Instrumentation– If pre and post tests are not equivalent in all

ways (e.g., difficulty, readability) then differences observed may be due to ‘instrumentation’ differences rather than due to your experimental manipulation.

Experimental Method:Experimental Method:Threats to Internal ValidityThreats to Internal Validity

Subject problems

– Selection bias (e.g., participation rate).

– Attrition (e.g., only motivated subjects stay in the experiment).

Experimental Method:Experimental Method:Threats to External ValidityThreats to External Validity

Subject variables– Selection bias.– Attrition bias

Artificial conditions– E.g., In order to measure a subject’s blood

pressure in response to a well-fined stressor you bring him/her into the laboratory but his/her response in the laboratory may not reflect how his/her blood pressure would really respond under stress in his natural environment.

Let me know…Let me know…

If there are any topics from today’s lecture that need fuller explanations.

Anything you particularly liked about the lecture (today’s or others as we go along).

Anything you particularly disliked about the lecture (today’s or others as we go along).