Sampling methods and experimental design

Question 1

What are the three types of experimental design?

Give a basic description of each

Answer 1

• Independent=Participant only takes part in one condition
• Repeated=Each participant takes part in both conditions and their performance is compared
• Matched pairs=Different participants are used in each condition but they are matched as closely as possible on key variables e.g IQ or age

Question 2

What are the strenghts and limitations of Independent Groups?

How can the limiations be overcome

Answer 2

• Strength=no order affects,less chance of demand characteristics
• Limitations=more P’s needed,partipant variables (individual differences)

Random allocation=allocate P’s to conditions without research methos

Question 3

What are the strengths and limitations of Matched Pairs?

Answer 3

• Strength=No order effects,Less chance of demand characteristics, Less chance of demand characteristics
• Limitations=Time consuming,more P’s needed,matching is difficult

Question 4

What are the strengths and limitations of Repeated Measures?

How can the limitations be overcome?

Answer 4

• Strength=Less P’s needed,removes individual differences
• Limitations=More materials needed,Order effects (able to practice or become bored)

Order effects can be overcome using counterbalancing

Question 5

What are the different sampling techniques?

Answer 5

Opportunity,Self-selected,Random,Systematic,Stratified and Snowball

Question 6

What are the strenghts and limitations of Opportunity + Self-selected sampling?

Answer 6

• Strengths=Quicker and more convenient than other sampling methods, able to get P’s who may otherwise be difficult to reach (self-selected)
• Limitations=Unrepresentative~research may choose people who are ‘helpful’ pr self-selceted only reach people at a certain time of day, sample is biased

Question 7

What are the strengths and limitations of random sampling?

Answer 7

• Strengths=For large sample it has the best chance of an unbiased representative sample,all members have an equal chane of being selected
• Limitations=time consuming to create a list of target pop for large populations,if sample is too small it could be biased

Question 8

What are the strengths and limitations of systematic sampling?

Answer 8

• Strength=sample is unbiased as it is selected by an objective system
• Limitation=Not completely random, not everyone has an equal chance of being selected

Question 9

What are the strengths and limitations of stratified sampling?

Answer 9

• Strengths=Delibirate effort to make sample representative,more representative than opportunity as there is equal representation of subgroups
• Limitations=Time consuming to identify subgroups and calculate proportions,use random or opportunity sampling

Question 10

What are the strengths and limitations of snowball sampling?

Answer 10

• Strengths=convenient and ethical if it leads to informed consent,access to wide variety of P’s which could make the sample more representative
• Limitations=sample will almost definetly be biased as all the P’s are likely to know each other and be from similar backgrounds or locations