Question

1-3 Questions are the ones that need to be answered from the experiemnt listed below.

1.Advantages for each technique. Provide at least two.

2.Disadvantages for each technique. Provide at least two.

3.Discuss the criteria used to determine the appropriateness of random assignment versus matching techniques

PSY-452-Experimental Psychology Matched-Subjects Design Separate the 40 participants listed below into two groups of 20, in which each group has an equal number of men and women (10 M, 10 F each). Use a random numbers table (text, pp. 537-538) to accomplish this. (Start anywhere in the table, and proceed in any direction that you like. Odd numbers put the subjects in group 1; even numbers in group 2. When one group is filled, the rest go into the other group.) Next, separate the participants into two groups by using range matching (decide on your acceptable ranges in advance, for example, within 5 pounds). Match as many pairs of female participants as possible: find a match and randomly assign one to the first group, and the other to the second group. Next, do the same for the male participants. Next, match not only on gender, but also on weight. Finally, match the participants on all three variables. Finally, match the 40 participants on gender, weight, and height, using rank-ordered matching.

Answer 1

The matched-subject design is in which though different subject groups are used for different conditions of independent variable still the researcher make sure that every subject of one group is equivalent to another subject of the other group.

Advantages

i) Since every subject is tested only once so it eliminates the possibility of temporal effects, e.g., order effect, so counterbalancing isn't necessary and the data obtained aren't biased.

ii) It reduces participant variable because each pair is matched in terms of abilities and characteristics.

Disadvantages

i) It is extremely difficult to find the exact matching pair though pairs are matched closely still not perfect and the process is time-consuming.

ii) If one participant drops out then the data collected on the paired participant also have to be rejected because it becomes useless.

The random assignment is in which each participant has an equal chance of being selected in any of the group to be tested for independent variable or control group.

Advantages

i) It ensures that participants in a study, e.g., cause and effect, are unbiased as it prevents people’s history from causing an extraneous variable within the experiment.

ii) It avoids effects of confounding variable and order effects, e.g., fatigue or practice, as a participant is subjected to one condition only.

Disadvantages

i) Differences between the participants, e.g., gender, socioeconomic status, education, affect the results.

ii) The number of participants required is more to put into different conditions and hence, time-consuming.  

Random assignment can be used when the number of subjects is more and the variable being studied prevails equally over the population and is less affected by the gender, sex, education ETC. And matching is necessary when the researcher is willing to all possible confounding and extraneous variable and wants to isolate the independent variable to the best possible extent.