method research designs and samples

Question 1

IV (Independent variable)

Answer 1

The IV is the condition that the experimenter systematically changes (or manipulates) in order to gauge its effect on another variable.
The IV is expected to cause a change in the dependent variable.
The IV is the suspected cause of difference in results between the control and experimental groups.

Question 2

DV (dependent variable)

Answer 2

*The DV is the result or effect that the IV has on behaviour.
*This is the variable that is being observed in the experimental situation

Question 3

EV (extraneous variable)

Answer 3

An extraneous variable is a variable other than the IV that may cause a change in the DV and therefore may affect the results.
they can make it difficult to conclude with confidence that any change in the DV was caused solely by the presence of the IV

Question 4

CV (controlled variable)

Answer 4

A controlled variable is a previously identified EV that is controlled during the course of the experiment.a controlled variable is not actually part of the experiment in itself. Nor is it a variable of interest in the investigation. But it is controlled because it could influence the outcome.

Question 5

CV (confounding variable)

Answer 5

A confounding variable is a variable other than the IV that has had an effect on the DV which cannot
be separated from that of the IV
If an experimenter does not identify all EVs prior to the experiment the variable may become confounding. Not all extraneous variables become confounding variables.

Question 6

population

Answer 6

the entire group of research interest from which a sample is drawn and to which the researcher will seek to generalise (apply) the results of their investigation.

Question 7

sample

Answer 7

a subset or part of the population that is selected for research purposes- the people who participate in the study.
Note: a large sample size is important, the more participants, the more likely they represent the population.

Question 8

Sampling Methods

Answer 8

random, stratified and convenience

Question 9

random sampling

Answer 9

a sampling technique that ensures every member of the population of research interest has an equal chance of being selected to be part of the sample.
This can be achieved by a random number generator or drawing names from a hat.

Question 10

random sampling limitations and advantages

Answer 10

Advantage- it helps ensure a highly representative sample, thereby enabling generalisations with greater confidence.

Limitation- it can only trulybe carried out if a complete list of the target population is available. If available, it may be difficult to gain access. If accessed, the process of random selection may be time-consuming.

Question 11

stratified sampling

Answer 11

Stratified sampling is the process of selecting a sample from a population comprised of various subgroups in such a way that each subgroup is represented. It involves dividing the population to be sampled into different subgroups (called strata), then selecting a separate sample from each subgroup (called stratum) in the same proportions as they occur in the population of interest.

Question 12

stratified sampling limitations and advantages

Answer 12

Advantages- It enables the researcher to sample specific groups (strata) within populations for comparison purposes for a MORE representative sample

Limitations- can be a very time-consuming and complex procedure, and therefore expensive procedure.

Question 13

convenience sampling

Answer 13

This is not a very good method of sampling since it can provide a biased sample but it is a commonly used one.
The researcher uses whoever is available at the time.

Question 14

Examples of convenience sampling include:

Answer 14

Asking people to volunteer via a newspaper article
Selecting people who walk past you in the school yard
Choosing participants because they are family, friends or classmates.

Question 15

Hypothesis

Answer 15

the hypothesis is an educated guess, based on what the experimenter believes they will find.

A research hypothesis is a testable prediction of the
relationship between two or more variables.

Question 16

Control group

Answer 16

Is the group in an experiment that does not receive the variable you are testing

Question 17

Experimental Groups

Answer 17

Is the group that receives the variable being tested in an experiment.

Question 18

Random Allocation

Answer 18

A procedure used to place participants in groups(or conditions) so that they are just as likely to be in the experimental group/s as the control group.

Question 19

Aim

Answer 19

A specific statement reflecting what the researcher wants to find out.

Question 20

Between subjects design

Answer 20

Each participant in the sample is randomly allocated to the control or experimental group(s).

Each group completes the condition they are assigned, then the results of each group are compared to see if the IV had an effect on the DV.

Question 21

Between design advantages and limitations

Answer 21

Advantages:
Quicker, as different participants are used in the experimental and control groups, so there is no need to spread out the time period between the different experimental conditions, unlike the ‘within subjects’ design.

Limitations:
Often a need for a larger sample to help ensure the spread of participant variables within the sample will match the distribution within the population.

In addition, there is less control over participant variables than in other designs, especially when a small sample is used

Question 22

within-subject design

Answer 22

Each participant is in both the experimental and control groupsor all the treatment conditions (if there is no control group).

Each group completes BOTH the control and experimental condition(s), then the results from each of the same conditions are added, we then see if the IV had an effect on the DV.

Question 23

within-subject design advantages and limitations

Answer 23

Advantages:
The groupsare identical in composition so individual participant differences may be controlled.
Tends to require a relatively smaller number of participants when compared with other designs because the same participants are in all conditions.

Limitations:
Participants gain ‘practice’ in completing the experiment.
Participants could be tired ‘fatigued’ and not try when the second condition is conducted.
Participants could be ‘bored’ and not try or engage properly in the second round of conditions. The issues can be fixed via ‘counterbalancing’ .

Question 24

mixed subject design

Answer 24

An investigation that combines features of both abetween subjects designand awithin subjects design.

This means that the researcher can assess the potential differences between two or more separate groups of participants (i.e. between subjects) as well as change in the individual members of each group over time (i.e. within subjects).

In its most simple form, a mixed design has two IV’s and each IV has two levels. One IV is ‘between subjects’ and one IV is ‘within subjects.

Question 25

mixed design advantages and limitations

Answer 25

Advantage:
The researcher can capitalise on the strengths of the between subjects and within subjects designs.

Fewer participants are needed for the experiment and there is greater sensitivity in the results; that is, they tend to be more precise and detailed.

Limitations:
Higher rate of participant withdrawal which could decrease internal validity

The limitations that are listed in the between and within subject designs, as a mixed design has elements of both of those designs.