Experiments

Question 1

How is a systematic sample selected? (3)

Answer 1

1. Create a sampling frame to organise target population e.g. put target population in alphabetical order
2. Decide on the system e.g. every 5th person
3. Continue until enough ppts for sample

Question 2

How is a stratified sample selected? (3)

Answer 2

1. Identify different sub groups that make up a population e.g. males/females
2. Calculate how many of each proportion you need for sample size
3. Number of participants which make up each proportion are chosen using random sampling

Question 3

How is an opportunity sample selected? (3)

Answer 3

1. Go somewhere you will have access to population you want to study
2. Ask first 30 ppts who are there at that moment
3. If they will take part

Question 4

How is a volunteer sample selected? (3)

Answer 4

1. Place an advert
2. Where people in target population will see it
3. Wait for the first 30 people to reply

Question 5

How to assess reliability of an experiment? (4)

Answer 5

TEST RE-REST
1. Participants are given a task to complete
2. Same participants given same task after time delay of 2 weeks
3. Correlate results from each test using stats test
4. A strong positive correlation of +0.8 shows high reliability

Question 6

How to conduct face validity? (3)

Answer 6

1. Independent psychologist in same field looks at the conditions
2. To see if they measure what they intend to measure
3. If the researcher says ‘yes’ then the research is valid

Question 7

How to conduct concurrent validity? (3)

Answer 7

1. Compare results of new test with results from another similar test that has already been established for its validity using a stats test
2. If results from both tests are similar, we can assume test is valid
3. Correlation of two results gained from stats test should exceed +0.8

Question 8

What is meant by a pilot study? (2)

Answer 8

1. Small scale trial run of the research before the real main scale research
2. Identify any problems and amend them

Question 9

Explain why a psychologist would conduct a pilot study. (3)

Answer 9

1. Check standardised instructions are clear for participants to understand what they are required to do in the experiment
2. Extraneous variables can be identified and removed
3. Any problems can be identified and adjusted before main study