Psychological InvestigationsG541 Revision

www.holah.co.uk/page/investigations

www.psychblog.co.uk/powerpoints

The Exam!• The exam is 1 hour long and you will have

to answer three questions.• This unit is 30% of your total AS psychology

- paper marked out of 60.• Although you will have to learn four

sections for this paper, you will only be asked questions on three of the sections.

Experiments

Correlations

Observations

Self-ReportsYou will be asked questions about:

•the piece of research including strengths and weaknesses. •the data produced by the research. •to design your own research •the strengths and weaknesses of this proposed research.

EXPERIMENTSPsychological Investigations

Experiments

Three types of experiments:

• Laboratory experiments – Highly controlled / artificial

• Field experiments– Controlled variables in a natural environment

• Quasi (natural) experiments– We have no control over the independent

variable – it’s ‘naturally’ occurring (eg Gender)

Experiments

Independent Variable

(IV)

Dependent Variable

(DV)

Confounding Variable: a variable that effects the DV

Extraneous Variable: a variable that could affect the DV but has been controlled for so it doesn’t.

Experiments

Extraneous Variables

Participant Variables• Independent Measures = Individual

Differences

Situational Variables• Any feature of the experiment that could

influence a participants behaviour

Single Blind – Double Blind – Control Groups

Experiments

• Independent Measures

• Participants are only in one condition.

Repeated Measures• The same participants

repeat the two conditions

Condition 1 Condition 2Condition 1 Condition 2

Counter balancing – alter order of Pp’s

Experiments

Matched Pairs – make two groups of participants as similar as possible.

Condition 1 Condition 2

Male (Bob)21IQ = 105

Male (Richard)21IQ = 105

Female (Dawn)25IQ = 115

Female (Cara)25IQ = 115

Strength Weakness

Independent Measures

No Order Effects Fewer Demand Characteristics

Individual Differences

Repeated Measures

No Individual Differences

Order Effects(counter balancing)

Matched Pairs

Controls for Individual

Differences

Can be difficult and costly.

Evaluation of Experimental Designs

Experimental Methods

Experimental Methods

±±

Independent & Dependent Variables

Independent & Dependent Variables

Confounding & Extraneous Variables

Confounding & Extraneous Variables

Cause & Effect

Cause & Effect

Types of Experiments

LaboratoryField

Quasi (natural)

Types of Experiments

LaboratoryField

Quasi (natural)

Independent Measures

Repeated Measures

Matched-Pairs

Independent Measures

Repeated Measures

Matched-Pairs

Sampling Methods

OpportunityRandomSnowballStratified

Self-Selected

Sampling Methods

OpportunityRandomSnowballStratified

Self-Selected

EthicsEthics

Ecological ValidityReliabilityValidity

Ecological ValidityReliabilityValidity

Experiments – Hypotheses

Participants memory will be much worse when there is a distraction in the room than when there is no distraction.

Participants memory will be much worse when there is a distraction in the room than when there is no distraction.

How are we measuring memory?

What’s better or worse? Higher /

Lower? More / Less?

What is the distraction? How are we manipulating it?

Operationalising your hypothesis

How have you manipulated your IV?How have you measured your DV?

Experiments – Hypotheses

Participants memory will be much worse when there is a distraction in the room than when there is no distraction.

Participants will remember significantly more words from a list of 20 presented for 60 seconds when they are in a room with no distractions than participants who are in a room where rock music is playing in the background.

Experiments – Hypotheses

Participants who [do something] will be significantly [faster/better/quicker etc] at [something] than participants who [do something else].

There will be no significant difference between participants who [do something] and those who [do something else]. Any difference will be down to chance.

Alte

rnat

ive

Nul

l

Experiments – Hypotheses

Participants who [do something] will be significantly [faster/better/quicker etc] at [something] than participants who [do something else].

There will be a significant difference between participants who [do something] and those who [do something else].

1Tailed

2Tailed

Key Terms - Experiments

• Laboratory Experiment• Field Experiment• Quasi Experiment• Independent Variable• Dependent Variable• Confounding Variable• Extraneous Variable• Replication• Cause and Effect• Ecological Validity• Alternative Hypothesis

• Demand Characteristics• Ethics• Independent Measures• Repeated Measures• Matched-Pairs• Individual Differences• Order Effects• Counter Balancing• Operationalising

Hypothesis• Null Hypothesis

CORRELATIONSPsychological Investigations

Correlation

• Positive Correlation• Negative Correlation• Zero Correlation

Can’t infer causation – only relationships!

Correlation Coefficients

+1.0 Perfect Positive

+0.8 Strong

+0.2 Weak

0 Zero

-0.2 Weak

-0.8 Strong

-1.0 Perfect Negative

Correlation – Hypotheses

There will be a significant [direction] correlation between [variable 1] (measured by [something]) and [variable 2] (measured by [something])

There will be no significant correlation between [variable 1] (measured by [something]) and [variable 2] (measured by [something])

Alte

rnat

ive.

Null

Correlation – Hypotheses

There will be a significant [direction] correlation between [variable 1] (measured by [something]) and [variable 2] (measured by [something])

There will be a significant correlation between [variable 1] (measured by [something]) and [variable 2] (measured by [something])

1Tailed

2Tailed

No Direction

Data Analysis

Descriptive Statistics

• Summary of data to illustrate patterns and relationships – BUT can’t infer conclusions

Inferential Statistics

• Statistical tests that allow us to make conclusions in relation to our hypothesis.

eg. Mann-Whitney or Spearman’s Rho.

Data AnalysisScattergram to show the

Correlation between variable 1 and variable 2

Titles are VERY important. Title your axis, the integers and give the graph a title.

Data Analysis

Descriptive Statistics

• Summary of data to illustrate patterns and relationships – BUT can’t infer conclusions

Inferential Statistics

• Statistical tests that allow us to make conclusions in relation to our hypothesis.

eg. Mann-Whitney or Spearman’s Rho.

Data AnalysisNominal - measure of central tendency: modeData in categories (finished, fell, started)

Ordinal - measure of central tendency: median Data which are ranked or in order (1st 2nd 3rd)

Interval - measure of central tendency: meanPrecise and measured using units of equal

intervals (1m54s, 1m59s, 2m03s)

Measure of dispersion = range (Highest – Lowest)

Key Terms - Correlation

• Positive Correlation• Negative Correlation• Zero Correlation• Causation• Correlation

Coefficient • Operationalise

Variables• Hypothesis

• One-tailed Hypothesis• Two-tailed Hypothesis• Alternate Hypothesis• Null Hypothesis• Descriptive Statistics• Inferential Statistics • Scattergram• Cause-and-effect

SELF-REPORTSPsychological Investigations

Self-Report

Data Types

Quantitative Data

Number data: easy to analyse – no meaning

Qualitative Data

Describing meaning: difficult to analyse

More valid – no interpretation needed

Self-Report

Questionnaires • Open Questions = Qualitative Data• Closed Questions = Quantitative Data

– Fixed Choice (yes / no)– Rating Scales (Likert-type Scales)

• Social Desirability & fibbing • Response rates & leading

questions

Types of SRHand Out

Face-to-facePhone

Email / InternetPostal

Self-Report

Interviews• Structured / Unstructured Interviews• Demand Characteristics / Social Desirability

Reliability – how consistent are the findings

Validity – does the question measure what is claims to measure?

Questionnaires: Split-Half MethodInterviews: Replicate them

Ask OPEN questions – more validConduct an observation of behaviour

±±Self

ReportsSelf

Reports

InterviewsStructured

Unstructured

InterviewsStructured

Unstructured

Data-TypesQuantitativeQualitative

Data-TypesQuantitativeQualitative

Types of SR’s

Postal / MailEmail / Web

Handout

TelephoneFace-to-Face

Types of SR’s

Postal / MailEmail / Web

Handout

TelephoneFace-to-Face

Sampling

OpportunitySelf-Selected

RandomStratified Snowball

Sampling

OpportunitySelf-Selected

RandomStratified Snowball

Reliability &ValiditySocial

Desirability

Reliability &ValiditySocial

Desirability

Question Types

Open / ClosedFixed Choice /

Likert

Question Types

Open / ClosedFixed Choice /

Likert

Sampling

General Population

Sample

Representative Sample Generalisations

Sampling Techniques

Sampling

Opportunity Sample

• People who are there at the time.

• Quick / Cheap / Easy• Not representative

Random Sample

• Each person in the GP has an equal chance of being chosen.

• Expensive and time consuming.

• Representative sample

Sampling

Self-Selected

• Participants volunteer to be in the sample following advert etc.

• Quick / Cheap / Easy• Not representative

What kind of person volunteers for a psychology experiment?

Snowball Sampling

• One person tells others who tell others …

• Allows us to collect difficult to locate people

• Time consuming

Key Terms - Self-Report

• Questionnaires• Interviews• Open Questions• Closed Questions• Social Desirability • Response Rate• Leading Questions• Unstructured Interviews• Quantitative Data• Qualitative Data• Likert Scales

• Fixed Choice• Reliability • Validity• Split-half method• Sampling• Opportunity Sample• Random Sample• Self-selected Sample• Stratified Sample• Snowball Sample

OBSERVATIONSPsychological Investigations

Observation

• Participant Observations– Take part in what you’re observing

• Non-Participant Observations– Just observe – no interaction

• Disclosed (overt) Observations– Participants aware of observer

• Undisclosed (covert) Observations– Participants unaware of observer Ethics!

Observer effectAct differently

Objectivity?

Observation

• Structured Observation– Coding scheme is used to record behaviour– Quantitative data collected

• Unstructured Observation– Researchers just record what’s going on– Qualitative data collected (usually)

• Controlled Observations– Researchers manipulate some variables

Event Sampling

Time Sampling

Observation - Sampling

Event Sampling• Coding Scheme• Researcher records

an event every time it happens.

• If too many things happen at once it may be difficult to record everything.

Time Sampling• Researcher decides

on a time and then records what is occurring at that time

• Some behaviours will be missed therefore the observation may not be representative.

Observation

Reliability

• Difficult to replicate observation – confounding variables.

• Check consistency within observations with inter-rater reliability (≥ 0.8)

• Improve reliability by using good coding scheme

Validity

• If participants know = low validity

• Observer bias = low validity

• Improve by using wider categories or single-blind technique

• Check validity by asking participants – self-report

Ethics

• Consent• Withdrawal• Debriefing • Deception• Confidentiality• Observation • Protection

• Advice• Colleagues

Key Terms - Observation

• Ecological Validity

• Non-participant Obs.

• Participant Obs.

• Undisclosed (covert)

• Disclosed (overt)

• Structured

• Unstructured

• Coding Scheme

• Controlled Observation

• Event Sampling• Time Sampling• Reliability • Inter-rater Reliability• Validity• Categories• Ethics• Quantitative Data• Qualitative Data

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© 2008 Jamie Davies

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