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Types of experiments; - Coggle Diagram
Types of experiments;
Experimental types;
Laboratory experiment; High control, participants randomly assigned to groups, IV is controlled.
Field experiment; Low level of control, IV is controlled.
Natural experiement; Low level of control, IV is not controlled.
Quasi experiments; Participants not randomly assigned to groups.
How to fix the weaknesses;
Counterbalancing; Mix up the order of the tasks, this can solve order effects in repeated measures design.
Random Allocation; Means that everyone has an equal chance of being in either condition A or B.
Standardised instructions - Instructions are pre-written and ensures that the experimenter acts in a similar way with all participants.
Randomisation; When material is presented to participants in a random order, this can help avoid order effects.
Evaluation;
Strengths;
Repeated measures - Not subject to individual variables. Don't need as many participants as they are used in all conditions.
Independents groups - No order effects. Data collection is faster as both conditions can be run at the same time (if possible).
Matched pairs - No order effects. Reduced risk of participant variables, as pairs are matched on similar traits.
Weaknesses;
Repeated measures - Order effect, participants may work out aims/be fatigued. If someone drops out, you loose data from both conditions.
Independent groups - More participants needed. Participant variable affecting results (eg; group one may be - due to random allocation - naturally smarter, more so than group 2).
Matched pairs - Lots of participants needed to take part in all conditions. Matching pairs is more complex, and you may not be able to match pairs identically.
Experimental design;
If you have decided that an experiment is the best approach to testing your hypothesis, then you need to design the experiment. Experimental design refers to how participants are allocated to the different conditions (or IV groups) in an experiment. 3 main types; Independent measures, repeated measures or matched pairs.
Independent group design; Different participants are used in each condition of the IV. This means that each condition of the experiment includes a different group of participants. This should be done by random allocation, which ensures that each participant has an equal chance of being assigned to one group or the other. Independent measures involved using two separate groups of participants, one for each condition.
Example; Group 1 = A, B, C, D, E --> in the noisy condition. Group 2 = F, G, H, I, J --> in the quiet condition.
Repeated measures design; The same participants take part in each condition of the IV. This means that each condition of the experiment includes the same group of participants.
Example; Only one group = A, B, C, D, E, F, G, H, I, J --> noisy condition then quiet condition.
Matched pairs design; One pair must be randomly assigned to the experimental group and the other to the control group. Paired based on characteristics eg; IQ, age etc.
Example; Pairs = A-B, C-D, E-F, G-H, I-J. Group 1 = A, C, E, G, I (noisy condition). Group 2 = B, D, F, H, J (quiet condition).