Pilot studies and Experimental design 🔨 Flashcards
What are pilot studies?
Pilot studies are a small-scale prototype of a study that are carried out in advance of the full research to find out if there are any problems with the following:
— Experimental design (enough time to complete task?)
— Instructions for participants (clear?)
— Measuring instruments (operationalised variables, questions etc)
Carrying out a pilot study beforehand is a way to ensure time, effort and money are not wasted on flawed methodology. It is important that a pilot study uses a sample that (although smaller) is representative of the target population that will be used in the main research.
What are the three types of experimental design?
1) Repeated measures
2) Independent groups
3) Matched pairs
What are repeated measures?
Repeated measures is a design where the same participants take part in each condition of the experiment.
— The data obtained from both conditions is then compared for each participant to see if there is a difference.
EVALUATION : Repeated Measures
STRENGTH - FEWER PARTICIPANTS NEEDED
P: A strength of repeated measures is that there are fewer participants needed since the same participants are taking part in all conditions of the experiment.
E: This makes the design less costly and time-consuming, as fewer participants need to be recruited.
E: In addition, the use of the same participants across the conditions reduces the possibility of participant variables such as individual differences playing a part in the different results obtained, meaning that the effect on the DV can be attributed to the IV with more confidence.
LIMITATION - ORDER EFFECTS + DEMAND CHARACTERISTICS
P: A limitation of using repeated measures as an experimental design is the fact it can create order effects.
E: As the same participants take part in both conditions of the experiment, participants who experience practice effects ,at perform better in the second condition as they know what is expected of them. Participants who experience fatigue (boredom) may perform worse in the second condition, because they give up.
E: To address the issues, researchers can use counterbalancing which offsets any order effects as half the participants take part in ‘Condition A’ followed by ‘Condition B’ while the other half complete ‘Condition B’ followed by ‘Condition A’. Any order effects experienced by those who started in Condition A should be offset by those starting in Condition B.
L: Furthermore, repeated measures experiments are also prone to demand characteristic s a participants are more likely to guess the aim of the experiment when they take part in both conditions.
What is an Independent Group?
An independent measures design uses of two separate groups of participants; one group in each condition of the experiment.
— Participants should be allocated to their group (condition) by random allocation, which ensures that each participant has equal chance of being assigned to one group or the other.
— This is important to reduce investigator bias, resulting in biased sample being placed into the two conditions, and influence of individual differences whereby participant variables influence the measurements taken in the DV.
EVALUATION : Independent Groups
STRENGTH - ORDER EFFECTS
P: A strength of using independent groups design is that it avoids order effects.
E: As participants only take part in one condition of the experiment, they are less likely to become bored and give up reducing the impact of order effects.
E: In addition, this research design also reduces demand characteristics, as participants are only taking part in one of the conditions of the experiment.
L: This means that they are less likely to guess the aim of the experiment and display demand characteristics, making the results higher invalidity.
LIMITATION - INDIVIDUAL DIFFERENCES + TIME CONSUMING/ EXPENSIVE
P: A disadvantage of using an independent groups design is that more participants are required as different people take part in the different conditions of the experiment.
E: This makes the design more expensive and time-consuming for the researcher who must recruit more individuals to take part.
E: Additionally, participant variables may affect the results. For example, differences in age, sex or social background may affect the results by acting as extraneous variables on the DV which mean that the psychologists cannot be certain that the IV caused the changes measured.
What are matched pairs design?
Pairs of participants are matched from a sample, in terms of key variables such as age or IQ.
— After matching takes place, the participates are treated much like those in independent measures.
— One member of each pair is placed in the experimental group and the other in the control group.
EVALUATION : Matched Pairs
STRENGTH - REDUCES PARTICIPANT VARIABLES
P: The benefit of adopting a matched pairs design is that it reduces participant variables.
E: The researcher pairs up the participants so that each condition has people with similar abilities and characteristics.
E: In addition, order effects (such as practice or fatigue)are less of an issue compared to a repeated measures design as the participants only take part in one of the conditions.
L: Therefore, participants are less likely to become bored and give up or guess the aims of the experiment.
LIMITATION - INDIVIDUAL DIFFERENCES
P: A drawback of using matched paired is that there is more participants needed and there are individual differences.
E: More participants are required, as different participants take part in the different conditions of the experiment, making the design more expensive and time-consuming for the researcher.
E: Furthermore, it is very difficult, not impossible , trying to find close or exactly matched pairs.
L: This means that individual differences may still play a role in the measurement of the DV reducing the certainty that the IV affected the change.
