In: Psychology
When random assignment is not used, which of the following is an issue that may result?
the number of people in each treatment group is not known
treatment groups may differ on pre-existing characteristics
you cannot use pretests
no issues arise; only random selection reduces possible issues
Random assignment refers to the use of chance procedures in psychology experiment to ensure that each participant has the same opportunity to be assigned to any given group.
Study participants are randomly assigned to different groups,such as the experimental group,or treatment group.Random assignment might involve such tactics as flipping a coin,drawing names out of a hat,rolling dice,or assigning random numbers of participants.This ensure that each participant or subject has a equal chance of being placed in any group.Random assignment of participants helps to ensure that any difference between and within the groups are not systematic at the outset of the experiment.thus, any difference between groups recorded at the end of the experiment can be more confidently attributed to the experimnetal procedure or treatment.
Benefits of random assignment :
Imagine an experiment in which the participants are not randomly assigned; perhaps the first 10 people to arrive are assigned to the experimental group, and the last 10 people to arrive are assigned to the control group.At the end of the experiment, the experimenter finds the difference between the experimental group and the control group, and claims these differences are a result of the experimental procedure. However, they also may be due to some other preexisting attribute of the participants,e.g.people who arrive early versus people who arrive late.
Randomness plays several important role in the design of experiment.In this case, we're talking about random assignment,which is different than random selection.
Random assignment helps ensure that members of each group in the experiment are the same, which means that the groups are also likely more representative of what is present in the larger population.