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Research Skills > Week 8 (variables, experimental research & non-experimental) > Flashcards

Week 8 (variables, experimental research & non-experimental) Flashcards

1
Q

What are the 3 classes of variables?

A

Behavioural
Stimulus
Subject

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2
Q

What is a behavioural variable?

A

It is any observable response produced by a subject

Eg. Often dependent variables the organism produces such as heart rate

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3
Q

What is a stimulus variable?

A

Environmental factors that have actual or potential effects on behavioural variables

Normally independent variables that we try to control

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4
Q

What are subject variables?

A

Characteristics that can be used to classify a subject for research purposes

Aren’t possible to control normally
Eg. Gender, age, mental health, medical condition

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5
Q

What is the dependent variable?

A

A variable that is measured or observed

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6
Q

How is the DV measured

?

A

Can be measured directly
Eg physical arousal, virus antibodies

Sometimes cannot be measured directly and is represented by a contrast
Eg pleasure, love, pain

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7
Q

What is the independent variable?

A

A variable that is manipulated by the researcher in true experiments

Requires at least 2 levels or conditions

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8
Q

When can the IV not be manipulated?

A

Sometimes it is impossible - eg sex

Sometimes it is unethical - eg smoking, drugs

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9
Q

What is an experiment called when they have more than one independent variable?

A

Factorial experiments

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10
Q

What is an operational definition?

A

Procedures or operations that specify how to manipulate or measure a construct

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11
Q

What are the benefits of multiple operational definitions?

A

Different aspects of the construct can be measured

Convergent validity

Allows for multiple ways to design studies

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12
Q

What are extraneous variables?

A

Variables other than the IV that affects the DV

Contribute to random (unexplained) error (variability) to the data

Systematically occur

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13
Q

What is a control variable?

A

Extraneous variables that are held constant to avoid confounding

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14
Q

What are the goals of experimental designs (3)?

A

Maximise (hypothesised) causal effect
Minimise influence of extraneous variables
Control confounding variables

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15
Q

What do experiments attempt to do in relation to between and in group designs?

A

Maximise between groups variance

Minimise within groups variance

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16
Q

Explain between groups variance?

A

Caused by an IV and is systematic

But can be affected by confounding variables that may act to increase difference between groups so that the IV appears more important than it is
Decrease differences between groups so that the IV appears less important than it is, masking IV effects

17
Q

Explain within groups variance

A

Variance typically caused by unknown factor - random (error) variance

Extraneous variables, individual differences and measurement error (unreliable instruments)

18
Q

Explain quasi-experimental designs

A

Inability to manipulate the IV
Unable to control all confounding variables
Can have control variables
Same statistical methods as experimental design

19
Q

Explain the process of a single group, post test only (one shot case study)?

A

Identify a sample
Introduce IV
Measure DV after intervention
Compare sample with others that haven’t had IV

No control group - poor quality study

20
Q

Why is a single group, post test only (one shot case study) under threat to its internal validity?

A 
Bias (sampling method) 
Maturation 
History 
Regression to the mean 
Placebo effects
21
Q

Explain the process of a single-group, protest-posttest experiment

A

Identify a sample
Measure DV before intervention (pre test)
Apply IV
Measure DV after intervention (post test)
Compare pretest and post test

Slightly stronger than single group post test only due to measurements prior to

22
Q

What are the threats to the internal validity in single-group, pretest-post test?

A 
Bias (sampling) 
Maturation 
History 
Regression to the mean 
Pre-test sensitisation 
Placebo effects
23
Q

Why should we use control groups and random assignment?

A

Control group reduces threats of history, maturation and regression to the mean

Random assignment reduces selection bias

24
Q

What is a two-group posttest-only, control group design?

A

Simplest form of between subjects design
Is a true experiment because of control for confounding variables and random assignment
Good to use when pre-testing isn’t possible

Process:
Sample split into control and experimental group
No treatment or apply IV
Measure DV after intervention and compare

25
Q

Explain 2group, pretest-post test

A

Simplest form of mixed design
True experimental design: random assignment
Controls maturation and history

Process:
Random allocation into control or experimental groups
Measure DV
Apply IV or not
Measure DV after
Calculate the effect by comparing post and pre tests

26
Q

What are the benefits of within subjects design?

A

Every participant is involved in every condition
Maximises group equivalence - perfect March when compared with self
Allows estimation of variance due to individual differences

Removes noise

27
Q

What are the issues with within-subject designs?

A

Order effects
Carry over effects
Sequence effects - condition order matters

28
Q

How do we minimise order effects in within subjects design?

A

Randomise condition order for each participant

For small number of conditions - complete counterbalancing eg. ABC ACB BAC BCA CAB CBA

partial counterbalancing - Latin square: each condition occurs one in each possible position
For large sample size!!

29
Q

What is a main effect?

A

Term only used in factorial designs

Effect of one factor, ignoring the other.
One main effect for each factor in the design

30
Q

What is an interaction effect?

A

Effect in which the effect of one factor depends on the levels of another factor

31
Q

Factorial designs and chi square analysis?

A

Chi square test of independence tests an interaction - will be significant if there is a large enough interaction

Does not test main effect - if there is a main effect but no interaction, test will not be significant

32
Q

How many operational definitions can a variable have?

A

A variable can have multiple operational definitions

Research Skills (12 decks)

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