Measurement Error Confounds

Question 1

Define Random error

Answer 1

A chance fluctuations in our measurement/ error by chance

Question 2

Define Constant or systematic error

Answer 2

A bias that is present and influences our
measurement in a systematic way

Question 3

Random errors (bias/obscure) the results
Constant errors (bias/obscure) the results

Answer 3

Random errors (obscure) the results
Constant errors (bias) the results

Question 4

What variables are undesirable variables that add error to our experiments?

Answer 4

Extraneous variables

Question 5

What are Extraneous variables?

Answer 5

Undesirable variables that add error
to our experiments

Question 6

What is the aim of research when it comes to Extraneous variables?

Answer 6

Aim = To eliminate or at least control the
influence of extraneous variables

Methods = Random allocation/counterbalancing which spreads the influence of extraneous variables

Question 7

Define internal validity

Answer 7

The degree of confidence that the causal relationship being tested is trustworthy and not influenced by other factors or variables

Simply = Is it valid in the lab/as a lab experiment?

Question 8

Define external validity

Answer 8

The extent to which you can generalise the findings of a study to other situations, people, settings, and measures

Simply = Can the results be applied/related to real-world settings?

Question 9

Define Confounding Variables

Answer 9

A 3rd variable in a study examining a potential cause and effect

It may mask or distort the effects of another variable

Question 10

What do Confounding variables measure?

Answer 10

1) An effect of the IV on the DV when it is not present

2) An effect of the IV on the DV when it is present

Question 11

What are the 4 main sources of confounding variables/threat to internal validity?

Answer 11

1) Selection
2) History
3) Maturation
4) Instrumentation

Question 12

How does “selection” cause a threat to internal validity?

Answer 12

Selection = Bias resulting from the selection or assignment of participants to different levels of the IV

e.g. Putting Psych students in 1 group and students from a different course with no prior knowledge of Psych in another group

Consequences = When you allocate Ps into groups unfairly but controlled selection and not random allocation, it could affect the measurement of the DV

Question 13

Why does selection error happen often in quasi-experiments?

Answer 13

Because quasi-experiments are unable to randomly allocate participants

(low internal validity but high external validity)

Question 14

How does “history” cause a threat to internal validity?

Answer 14

History = Uncontrolled events that take place between testing occasions

e.g. Testing a group of people with alcohol in the morning and another group with alcohol in the afternoon

There could be a change that occurs during the day that makes the testing situation different (maybe more traffic noise in the afternoon, more distracting)

Question 15

How does “maturation” cause a threat to internal validity?

Answer 15

Maturation = Intrinsic changes in the characteristics of participants between
different test occasions

e.g. In within-subjected design, participants get older and more mature which may affect their performance

Question 16

Why does maturation error happen often in within-subjects experiments?

Answer 16

Because WS is a longitudinal study (study participants over time) and Ps may have matured a lot since the last testing session

Question 17

How does “instrumentation” cause a threat to internal validity?

Answer 17

Instrumentation = Changes in the sensitivity or reliability of measurement instruments during the course of the study

e.g. Some measuring devices may become less sensitive when they deteriorate and may affect measurements of DV

Question 18

What is Reactivity in Validity?

Answer 18

When Ps or experimenters are aware that they are being observed and they may alter their behaviour

Question 19

What are the 2 types of reactivity?

Answer 19

1) Subject-related reactivity

2) Experimenter related

Question 20

What is Subject-related reactivity?

Answer 20

When participants behave how they think the researchers want them to behave (they may be aware of the aims of the experiment and which experimental condition they are under)

Question 21

What is Experimenter-related reactivity?

Answer 21

When experimenters give inadvertent verbal/non-verbal cues to the participants that could bias the results (they may be aware of which experimental condition the Ps are under)

Question 22

How do you overcome reactivity?

Answer 22

Blind procedures

Question 23

What are blind procedures?

Answer 23

Information which may influence the participants and/or experimenters of the experiment is withheld until after the experiment is complete

Question 24

What is a single and what is a double blind procedure?

Answer 24

Single = When only participants are unaware of the IVs of the study in which they are operating in

Double = When both the participants and experimenters are unaware of the IVs of the study in which the participants are operating in

Question 25

You are measuring the height of women and make small errors reading the tape measure. Are these errors…

a. Random

b. Constant

Answer 25

A

Question 26

You forget to ask the women to take their shoes off before you measure them. Are these measures…

a.	Random

b.	Constant

Answer 26

B

Question 27

You weigh participants on a set of scales that are not set to zero. Are these errors…

a.	Random

b.	Constant

Answer 27

B

Question 28

Which of the following is not a common threat to internal validity?

a.	Maturation

b.	Iteration

c.	Selection

d.	History

Answer 28

B

Question 29

Which of the following statements is correct?

a.	Random errors obscure the results, Constant errors bias the results

b.	Constant errors obscure the results, Random errors bias the results

c.	Constant errors tend to push the measurements up and down around the exact value

d.	Random errors tend to push the measurements in the same direction

Answer 29

A

Question 30

Intrinsic changes in the characteristics of participants between different test occasions is a threat to internal validity as a result of…

a.	Selection

b.	History

c.	Maturation

d.	Instrumentation

Answer 30

C

Question 31

You set out to determine the effect of mobile phone use on hazard awareness while driving. On the first occasion, you ask participants to identify potential hazards during a driving simulation with no distracter. On the second occasion, you ask the same participants to repeat the task while talking on a mobile phone.

a. Solution to confound
b. Subjects design
c. Confound
d. Dependent variable
e. Hypothesis
f. Independent variable

1. Talking on a mobile will reduce drivers’ ability to identify hazards
2. Mobile use- with versus without
3. Number of distractors identified
4. Within-subjects/ Repeated measures
5. Maturation: order effects (practice/fatigue)
6. Counterbalance conditions across participants

Answer 31

1. E
2. F
3. D
4. B
5. C
6. A

Question 32

You want to determine whether the introduction of social media tools has made children feel more or less isolated. You compare children’s ratings of loneliness in 2011 with children’s ratings of loneliness in 1991.

a. Confound
b. Subjects design
c. Independent variable
d. Hypothesis
e. Dependent variable

1. Children will obtain higher/lower scores on loneliness measures following the introduction of social media
2. Pre/post social media 2011/1991
3. Score on loneliness measure
4. Between/independent
5. History: other changes that could impact the DV (e.g. rise in mobile phone use/ email communication).

Answer 32

1. D
2. C
3. E
4. B
5. A