effect of extraneous variables

Question 1

describe how extraneous variables can affect validity.

Answer 1

if some extraneous variables arent controlled, then the study might not be measuring what it claims to be measuring, thus, decreasing the validity of the study.

Question 2

describe how extraneous variables can affect reliability.

Answer 2

if some extraneous variables arent controlled, then we might get different results on different trial of the experiment, thus decreasing the external reliability of the experiment.

Question 3

What are the 3 ways in which w ecan control extraneous variables?

Answer 3

1. standardisation.
2. matching
3. random allocation.

Question 4

describe standardisation.

Answer 4

this means when a researcher makes an extraneous variable the same for all participants, so that validity, and reliability increases.

We can only use it to control situational variables, and investigator effects, but NOT participant variables.

Question 5

describe how matching can control extraneous variables.

Answer 5

when researchers allocate participants to experimental and control groups, to make sure that a participant variable is devided equally across both groups.

Question 6

describe the dissadvantages of mathching.

Answer 6

1. time consuming: researcher has to measure personal characteristics of participant, and then try to identify participants with similar characteristics.
2. cant control every possible participant, therefore some participant vriables might still affect the experiment.

Question 7

describe how random allocation can help control extraneous variables.

Answer 7

participants are asigned at random, so that they have an EQUAL chance of being allocated to either group

It is very likely for participant variables to be distributed evenly.

Question 8

Describe what is meand by blinding.

Answer 8

When the participants dont know which experimental group they are in.

Question 9

describe how blinding can help stop demand characteristics, and investigator effects.

Answer 9

1. demand characteristics: dont know which group they are in, therefore harder to figure out the aim of the study.
2. investigatore effects: They can tell another researcer to conduct the study for them, so that there is no personal bias involved.

Question 10

what is a single blind study?

Answer 10

When only the participants are blinded.

Question 11

what is a diuble blind study?

Answer 11

When both the participants and the researcher are blinded.