1.4 preventing error + bias

Question 1

Examples of extraneous + confounding variables

Answer 1

• Participant-related variables
• Order effects
• Placebo effects
• Experimenter effects
• Situational variables
• Non-standardised instructions + procedures
• Demand characteristics

Question 2

Participant-related variables

Answer 2

Characteristics of a study’s participants that may effect results (eg.age, intelligence, socioeconomic status).

Question 3

Order effects

Answer 3

Order in which participants complete conditions has an effect on their behaviour (eg. practise, fatigue).

Question 4

Placebo effects

Answer 4

When participants respond to an inactive substance or treatment as a result of their expectations or beliefs.

Question 5

Experimenter effects

Answer 5

Expectations of the research effect the experiment.

Question 6

Situational variables

Answer 6

Any environmental factor that may effect the DV (eg. temperature, lighting, weather).

Question 7

Non-standardised instructions + procedures

Answer 7

Directions + procedures differ across participants/experimental conditions.

Question 8

Demand characteristics

Answer 8

Cues in an experiment that signal the intention of an experiment to a participant + influence their behaviour.

Question 9

Preventing extraneous + confounding variables

Answer 9

• Sampling size + procedures
• Experimental design choice
• Counterbalancing
• Placebo
• Single-blind procedures
• Double-blind procedures
• Standardised testing conditions + procedures
• Controlled variables

Question 10

Sampling size + procedures

Answer 10

A larger sample size = outlier may not have as much of an effect.
- Participant-related variables.

Question 11

Experimental design choice

Answer 11

Order effects - if within-subjects design isn’t used.
Participant-related variables - if within-subjects is used.

Question 12

Counterbalancing

Answer 12

Order experimental conditions in a certain way.
- Order effects

Question 13

Placebo

Answer 13

Compare the results of participants given an active intervention, with those who are in the controlled placebo group.
- Placebo effects

Question 14

Single-blind procedures

Answer 14

Participants are unaware of the experimental condition they ahve been assigned to.
- Participant-related variables + expectations, demand characteristics, placebo effects.

Question 15

Double-blind procedures

Answer 15

Participants + researchers don’t know which conditions participants are allocated to.
- Experimenter effects, participant expectations, demand characteristics.

Question 16

Standardised instructions + procedures

Answer 16

Ensuring each participant/group receives exact same instructions + procedures to ensure changes are solely due to IV.
- Situational variables, non-standardised conditions + procedures, demand characteristics.

Question 17

Controlled variables

Answer 17

The effect of EV is systematically minimised + accounted for.