Question

1. The primary rule of subject selection for experimental designs is the comparability of experimental and control groups. Ideally, the control group would be identical to the experimental group if it had not been exposed to the experimental stimulus. Therefore, the experimental and control groups should be as similar as possible. Probability sampling, randomization, and matching are several different methods for achieving this similarity.

One technique for ensuring an appropriate control group is the process of selecting multiple samples from a population using a method that is subject to chance rather than the bias of the experimenter and then assigning each sample to either an experimental or a control group. This technique is called A.PROBABILITY SAMPLING B. RANDOMIZATION

C. MATCHING

2. Nikhil is interested in finding out whether reading a comic strip about euthanasia will change people’s opinions on the subject. Nikhil decides to recruit a group of subjects and then divide the group into subgroups of older and younger students of each ethnicity. He then assigns half of each subgroup to be part of the experimental group and half to the control group, so that the experimental and control groups have the same makeup in terms of age and ethnicity. Nikhil administers a pretest to everyone to measure their opinions about euthanasia. Then the experimental group is asked to read the comic strip and the control group is not. Finally, Nikhil administers a posttest to everyone to see if their opinions about euthanasia have changed.

Which technique is Nikhil employing to ensure that the experimental and control groups are equivalent? A. Matching B. Randomization C. Probability sampling

3. The three different techniques have different advantages and disadvantages. In which of the following ways is randomization a better choice than matching? Check all that apply.

A. You do not necessarily know in advance which variables will be the most relevant for the study.

B.Randomization allows for conscious stratification.

C. Most of the statistics used to analyze the results of experiments assume randomization.

Answer 1

Ans: 1.The process of selecting multiple samples from a population using a method that is subject to chance rather than bias of the experimenter and then assigning each sample to either experimental or control group using random digit table or random digit simulator is called RANDOMIZATION.

2.What Nikhil is employing here is called matched pair design where group of subjects are already blocked by age and ethnicity of younger and old age group and each of this sub group are further randomly assigned equally to experimental and control group.Nikhil further administers all the subjects in these subgroups with their opinion on euthanasia and then ask only the subjects in experimental group to read comic strips while the subjects in control group are not provided with any comic strip through post tests.This way matching the effect of comic strips among experimental and control group are properly recorded to minimize the variability as well as by applying randomization.This method in sampling design is called A.MATCHING exactly.

3.Randomization a better choice than matching in the scenarios where A.You do not necessarily know in advance which variables will be the most relevant for the study for blocking etc and also we employ randomization to control variability and therefore C.Most of the statistics used to analyze the results of experiments assume randomization.