GCSE psychology sampling, methods and designs

Which of the following is a disadvantage of 'matched pairs'?

• There will be order effects

• There will be a high level of participant variables

• It is difficult to match participants exactly

• There may be demand characteristics

Answer explanation

Matched pairs is where you pair participants together as closely as possible (such as gender, age, ability), before one of the pair does one condition whilst one does the other. Whilst this has many advantages, there still may be differences between them that may affect the results

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Experimental design

Which 'experimental design' produces the highest amount of participant variables?

• Independent groups

• Matched pairs

• Repeated measures

Answer explanation

Participant variables is where there is a large difference in the participants doing one condition compared to the other condition. Independent groups is where some participants take part in one condition, and another set of participants take part in the other condition. This means that there is no control over whether the participants doing each condition are alike, so there is likely to be a high level of participant variables.

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Experimental design

Which 'experimental design' does this picture show?

• Independent groups

• Repeated measures

• Matched pairs

Answer explanation

Repeated measures is where the same people take part in both conditions of the experiment. This picture shows that the same participants are taking part in both condition A and condition B.

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Experimental design

Please tick ALL the statements below that refer to 'opportunity sampling':

• It is quick and easy to produce

• The sample is likely to be very biased

• The sample is not likely to be representative

• The sample will always contain a mix of genders

Answer explanation

Opportunity sampling simply involves choosing whoever is available at the time. This makes it very quick and easy, but also means the researcher can choose who he wants, so can be heavily biased. It is also very unlikely to be a representative sample.

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Sampling methods

Please tick ALL of the statements that are true for systematic sampling:

• The sample avoids researcher bias

• The sample will be representative

• The sample is created by choosing every nth person from a list

• The sample always produces an equal amount of each gender

Answer explanation

Systematic sampling involves arranging the participants in a particular order (such as alphabetically), and then choosign every nth person (e.g. every 3rd person) until you have enough participants. This means that there cannot be any researcher bias, but there is no guarantee that the sample will be representative - there is a chance that all of the participants may be similar (e.g. in terms of age or gender)

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Sampling methods

Please tick ALL of the statements that are true for stratified sampling:

• The sample avoids researcher bias

• The sample is likely to be representative

• The sample involves selecting participants from each sub group of the target population

• The sample is quick and easy to create

Answer explanation

Stratified sampling involves ensuring that each sub group (such as age, gender, ability) are represented in the correct proportion within the sample. It is therefore very representative, but can take a long time to produce.

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Sampling methods

Please tick ALL of the statements that are true for random sampling:

• The sample avoids researcher bias

• The sample is likely to be representative

• The sample can be created using a digital selector

• The sample will always contain an equal amount of each gender

Answer explanation

Random sampling involves using a technique to randomly select the participants (such as picking names out of a hat or using a digital selector). This removes any kind of researcher bias, but there is no guarantee that the sample will be representative.

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Sampling methods

Which variable within an experiment is the one that is changed to see what effect is has?

• Independent variable

• Dependent variable

• Extraneous variable

• Confounding variable

Answer explanation

The independent variable is the aspect of the experiment that the researcher will change in order to see what effect it has.

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Variables

Which variable within an experiment is the one that is measured?

• Independent variable

• Dependent variable

• Extraneous variable

• Confounding variable

Answer explanation

The dependent variable is the aspect of the experiment that is measure to see what effect has been caused.

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Variables

Which variable within an experiment is the one that needs to be controlled so that it doesn't accidentally affect the results?

• Independent variable

• Dependent variable

• Extraneous variable

• Confounding variable

Answer explanation

Extraneous variables are the variables that are not directly linked to the experiment, but need to be controlled so that they don't affect results. Examples include issues such as where the experiment takes place, the time of the day, the ages of the participants, etc.

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Variables